Processes to produce short-cut microfibers

ABSTRACT

A process for producing a microfiber product stream, the process comprises: (A) contacting cut multicomponent fibers having a length of less than 25 millimeters with a treated aqueous stream in a fiber slurry zone to produce a cut multicomponent fiber slurry; (B) contacting the cut multicomponent fiber slurry with a heated aqueous stream in a mix zone to produce a heated multicomponent fiber slurry; (C) routing the heated multicomponent fiber slurry to a fiber opening zone to remove a portion of the water dispersible sulfopolyester to produce an opened microfiber slurry; wherein the opening zone comprises a pipe reactor; and (D) routing the opened microfiber slurry to a primary solid liquid separation zone to produce the microfiber product stream and a first mother liquor stream.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/687,505, now allowed, and claims priority to U.S. patent applicationSer. No. 13/687,505 and U.S. Provisional Application Nos. 61/592,854,61/592,867; 61/592,917; and 61/592,974 filed on Jan. 31, 2012, thedisclosures of which are incorporated herein by reference to the extentthey do not contradict the statements herein.

FIELD OF THE INVENTION

The present invention pertains to water-dispersible fibers and fibrousarticles comprising a sulfopolyester. The invention further pertains tomulticomponent fibers comprising a sulfopolyester and the microdenierfibers and fibrous articles prepared therefrom. The invention alsopertains to processes for producing water-dispersible, multicomponent,and microdenier fibers and to articles produced therefrom.

BACKGROUND OF THE INVENTION

Fibers, melt blown webs and other melt spun fibrous articles have beenmade from thermoplastic polymers, such as poly(propylene), polyamides,and polyesters. One common application of these fibers and fibrousarticles are nonwoven fabrics and, in particular, in personal careproducts such as wipes, feminine hygiene products, baby diapers, adultincontinence briefs, hospital/surgical and other medical disposables,protective fabrics and layers, geotextiles, industrial wipes, and filtermedia. Unfortunately, the personal care products made from conventionalthermoplastic polymers are difficult to dispose of and are usuallyplaced in landfills. One promising alternative method of disposal is tomake these products or their components “flushable”, i.e., compatiblewith public sewerage systems. The use of water-dispersible orwater-soluble materials also improves recyclability and reclamation ofpersonal care products. The various thermoplastic polymers now used inpersonal care products are not inherently water-dispersible or solubleand, hence, do not produce articles that readily disintegrate and can bedisposed of in a sewerage system or recycled easily.

The desirability of flushable personal care products has resulted in aneed for fibers, nonwovens, and other fibrous articles with variousdegrees of water-responsivity. Various approaches to addressing theseneeds have been described, for example, in U.S. Pat. Nos. 6,548,592;6,552,162; 5,281,306; 5,292,581; 5,935,880; and 5,509,913; U.S. patentapplication Ser. Nos. 09/775,312; and 09/752,017; and PCT InternationalPublication No. WO 01/66666 A2. These approaches, however, suffer from anumber of disadvantages and do not provide a fibrous article, such as afiber or nonwoven fabric, that possesses a satisfactory balance ofperformance properties, such as tensile strength, absorptivity,flexibility, and fabric integrity under both wet or dry conditions.

For example, typical nonwoven technology is based on themultidirectional deposition of fibers that are treated with a resinbinding adhesive to form a web having strong integrity and otherdesirable properties. The resulting assemblies, however, generally havepoor water-responsivity and are not suitable for flushable applications.The presence of binder also may result in undesirable properties in thefinal product, such as reduced sheet wettability, increased stiffness,stickiness, and higher production costs. It is also difficult to producea binder that will exhibit adequate wet strength during use and yetdisperse quickly upon disposal. Thus, nonwoven assemblies using thesebinders may either disintegrate slowly under ambient conditions or haveless than adequate wet strength properties in the presence of bodyfluids. To address this problem, pH and ion-sensitive water-dispersiblebinders, such as lattices containing acrylic or methacrylic acid with orwithout added salts, are known and described, for example, in U.S. Pat.No. 6,548,592 B1. Ion concentrations and pH levels in public sewerageand residential septic systems, however, can vary widely amonggeographical locations and may not be sufficient for the binder tobecome soluble and disperse. In this case, the fibrous articles will notdisintegrate after disposal and can clog drains or sewer laterals.

Multicomponent fibers containing a water-dispersible component and athermoplastic water non-dispersible component have been described, forexample, in U.S. Pat. Nos. 5,916,678; 5,405,698; 4,966,808; 5,525,282;5,366,804; 5,486,418. For example, these multicomponent fibers may be abicomponent fiber having a shaped or engineered transverse cross sectionsuch as, for example, an islands-in-the-sea, sheath core, side-by-side,or segmented pie configuration. The multicomponent fiber can besubjected to water or a dilute alkaline solution where thewater-dispersible component is dissolved away to leave the waternon-dispersible component behind as separate, independent fibers ofextremely small fineness. Polymers which have good water dispersibility,however, often impart tackiness to the resulting multicomponent fibers,which causes the fiber to stick together, block, or fuse during windingor storage after several days, especially under hot, humid conditions.To prevent fusing, often a fatty acid or oil-based finish is applied tothe surface of the fiber. In addition, large proportions of pigments orfillers are sometimes added to water dispersible polymers to preventfusing of the fibers as described, for example, in U.S. Pat. No.6,171,685. Such oil finishes, pigments, and fillers require additionalprocessing steps and can impart undesirable properties to the finalfiber. Many water-dispersible polymers also require alkaline solutionsfor their removal which can cause degradation of the other polymercomponents of the fiber such as, for example, reduction of inherentviscosity, tenacity, and melt strength. Further, some water-dispersiblepolymers can not withstand exposure to water during hydroentanglementand, thus, are not suitable for the manufacture of nonwoven webs andfabrics.

Alternatively, the water-dispersible component may serve as a bondingagent for the thermoplastic fibers in nonwoven webs. Upon exposure towater, the fiber to fiber bonds come apart such that the nonwoven webloses its integrity and breaks down into individual fibers. Thethermoplastic fiber components of these nonwoven webs, however, are notwater-dispersible and remain present in the aqueous medium and, thus,must eventually be removed from municipal wastewater treatment plants.Hydroentanglement may be used to produce disintegratable nonwovenfabrics without or with very low levels (<5 weight %) of added binder tohold the fibers together. Although these fabrics may disintegrate upondisposal, they often utilize fibers that are not water soluble orwater-dispersible and may result in entanglement and plugging withinsewer systems. Any added water-dispersible binders also must beminimally affected by hydroentangling and not form gelatinous buildup orcross-link, and thereby contribute to fabric handling or sewer relatedproblems.

A few water-soluble or water-dispersible polymers are available, but aregenerally not applicable to melt blown fiber forming operations or meltspinning in general. Polymers, such as polyvinyl alcohol, polyvinylpyrrolidone, and polyacrylic acid are not melt processable as a resultof thermal decomposition that occurs at temperatures below the pointwhere a suitable melt viscosity is attained. High molecular weightpolyethylene oxide may have suitable thermal stability, but wouldprovide a high viscosity solution at the polymer interface resulting ina slow rate of disintegration. Water-dispersible sulfopolyesters havebeen described, for example, in U.S. Pat. Nos. 6,171,685; 5,543,488;5,853,701; 4,304,901; 6,211,309; 5,570,605; 6,428,900; and 3,779,993.Typical sulfopolyesters, however, are low molecular weightthermoplastics that are brittle and lack the flexibility to withstand awinding operation to yield a roll of material that does not fracture orcrumble. Sulfopolyesters also can exhibit blocking or fusing duringprocessing into film or fibers, which may require the use of oilfinishes or large amounts of pigments or fillers to avoid. Low molecularweight polyethylene oxide (more commonly known as polyethylene glycol)is a weak/brittle polymer that also does not have the required physicalproperties for fiber applications. Forming fibers from knownwater-soluble polymers via solution techniques is an alternative, butthe added complexity of removing solvent, especially water, increasesmanufacturing costs.

Accordingly, there is a need for a water-dispersible fiber and fibrousarticles prepared therefrom that exhibit adequate tensile strength,absorptivity, flexibility, and fabric integrity in the presence ofmoisture, especially upon exposure to human bodily fluids. In addition,a fibrous article is needed that does not require a binder andcompletely disperses or dissolves in residential or municipal seweragesystems. Potential uses include, but are not limited to, melt blownwebs, spunbond fabrics, hydroentangled fabrics, wet-laid nonwovens,dry-laid non-wovens, bicomponent fiber components, adhesive promotinglayers, binders for cellulosics, flushable nonwovens and films,dissolvable binder fibers, protective layers, and carriers for activeingredients to be released or dissolved in water. There is also a needfor multicomponent fiber having a water-dispersible component that doesnot exhibit excessive blocking or fusing of filaments during spinningoperations, is easily removed by hot water at neutral or slightly acidicpH, and is suitable for hydroentangling processes to manufacturenonwoven fabrics. These multicomponent fibers can be utilized to producemicrofibers that can be used to produce various articles. Otherextrudable and melt spun fibrous materials are also possible.

SUMMARY OF THE INVENTION

We have unexpectedly discovered that flexible, water-dispersible fibersmay be prepared from sulfopolyesters. Thus the present inventionprovides a water-dispersible fiber comprising:

(A) a sulfopolyester having a glass transition temperature (Tg) of atleast 25° C., the sulfopolyester comprising:

-   -   (i) residues of one or more dicarboxylic acids;    -   (ii) about 4 to about 40 mole %, based on the total repeating        units, of residues of at least one sulfomonomer having 2        functional groups and one or more sulfonate groups attached to        an aromatic or cycloaliphatic ring wherein the functional groups        are hydroxyl, carboxyl, or a combination thereof;    -   (iii) one or more diol residues wherein at least 25 mole %,        based on the total diol residues, is a poly(ethylene glycol)        having a structure

H—(OCH2-CH2)n-OH

-   -   wherein n is an integer in the range of 2 to about 500; and    -   (iv) 0 to about 25 mole %, based on the total repeating units,        of residues of a branching monomer having 3 or more functional        groups wherein the functional groups are hydroxyl, carboxyl, or        a combination thereof;

(B) optionally, a water-dispersible polymer blended with thesulfopolyester; and

(C) optionally, a water non-dispersible polymer blended with thesulfopolyester with the proviso that the blend is an immiscible blend;wherein the fiber contains less than 10 weight % of a pigment or filler,based on the total weight of the fiber.

The fibers of the present invention may be unicomponent fibers thatrapidly disperse or dissolve in water and may be produced bymelt-blowing or melt-spinning. The fibers may be prepared from a singlesulfopolyester or a blend of the sulfopolyester with a water-dispersibleor water non-dispersible polymer. Thus, the fiber of the presentinvention, optionally, may include a water-dispersible polymer blendedwith the sulfopolyester. In addition, the fiber may optionally include awater non-dispersible polymer blended with the sulfopolyester, providedthat the blend is an immiscible blend. Our invention also includesfibrous articles comprising our water-dispersible fibers. Thus, thefibers of our invention may be used to prepare various fibrous articles,such as yarns, melt-blown webs, spunbonded webs, and nonwoven fabricsthat are, in turn, water-dispersible or flushable. Staple fibers of ourinvention can also be blended with natural or synthetic fibers in paper,nonwoven webs, and textile yarns.

Another aspect of the present invention is a water-dispersible fibercomprising:

(A) a sulfopolyester having a glass transition temperature (Tg) of atleast 25° C., the sulfopolyester comprising:

-   -   (i) about 50 to about 96 mole % of one or more residues of        isophthalic acid or terephthalic acid, based on the total acid        residues;    -   (ii) about 4 to about 30 mole %, based on the total acid        residues, of a residue of sodiosulfoisophthalic acid;    -   (iii) one or more diol residues wherein at least 25 mole %,        based on the total diol residues, is a poly(ethylene glycol)        having a structure

H—(OCH2-CH2)n-OH

-   -   wherein n is an integer in the range of 2 to about 500;    -   (iv) 0 to about 20 mole %, based on the total repeating units,        of residues of a branching monomer having 3 or more functional        groups wherein the functional groups are hydroxyl, carboxyl, or        a combination thereof;

(B) optionally, a first water-dispersible polymer blended with thesulfopolyester; and

(C) optionally, a water non-dispersible polymer blended with thesulfopolyester to form a blend with the proviso that the blend is animmiscible blend;

wherein the fiber contains less than 10 weight % of a pigment or filler,based on the total weight of the fiber.

The water-dispersible, fibrous articles of the present invention includepersonal care articles such as, for example, wipes, gauze, tissue,diapers, training pants, sanitary napkins, bandages, wound care, andsurgical dressings. In addition to being water-dispersible, the fibrousarticles of our invention are flushable, that is, compatible with andsuitable for disposal in residential and municipal sewerage systems.

The present invention also provides a multicomponent fiber comprising awater-dispersible sulfopolyester and one or more water non-dispersiblepolymers. The fiber has an engineered geometry such that the waternon-dispersible polymers are present as segments substantially isolatedfrom each other by the intervening sulfopolyester, which acts as abinder or encapsulating matrix for the water non-dispersible segments.Thus, another aspect of our invention is a multicomponent fiber having ashaped cross section, comprising:

(A) a water dispersible sulfopolyester having a glass transitiontemperature (Tg) of at least 57° C., the sulfopolyester comprising:

-   -   (i) residues of one or more dicarboxylic acids;    -   (ii) about 4 to about 40 mole %, based on the total repeating        units, of residues of at least one sulfomonomer having 2        functional groups and one or more sulfonate groups attached to        an aromatic or cycloaliphatic ring wherein the functional groups        are hydroxyl, carboxyl, or a combination thereof;    -   (iii) one or more diol residues wherein at least 25 mole %,        based on the total diol residues, is a poly(ethylene glycol)        having a structure

H—(OCH₂—CH₂)_(n)—OH

-   -   wherein n is an integer in the range of 2 to about 500; and    -   (iv) 0 to about 25 mole %, based on the total repeating units,        of residues of a branching monomer having 3 or more functional        groups wherein the functional groups are hydroxyl, carboxyl, or        a combination thereof; and

(B) a plurality of segments comprising one or more water non-dispersiblepolymers immiscible with the sulfopolyester, wherein the segments aresubstantially isolated from each other by the sulfopolyester interveningbetween the segments.

The sulfopolyester has a glass transition temperature of at least 57° C.which greatly reduces blocking and fusion of the fiber during windingand long term storage.

The sulfopolyester may be removed by contacting the multicomponent fiberwith water to leave behind the water non-dispersible segments asmicrodenier fibers. Our invention, therefore, also provides a processfor microdenier fibers comprising:

(A) spinning a water dispersible sulfopolyester having a glasstransition temperature (Tg) of at least 57° C. and one or more waternon-dispersible polymers immiscible with the sulfopolyester intomulticomponent fibers, the sulfopolyester comprising:

-   -   (i) about 50 to about 96 mole % of one or more residues of        isophthalic acid or terephthalic acid, based on the total acid        residues;    -   (ii) about 4 to about 30 mole %, based on the total acid        residues, of a residue of sodiosulfoisophthalic acid;    -   (iii) one or more diol residues wherein at least 25 mole %,        based on the total diol residues, is a poly(ethylene glycol)        having a structure

H—(OCH₂—CH₂)_(n)—OH

-   -   wherein n is an integer in the range of 2 to about 500; and    -   (iv) 0 to about 20 mole %, based on the total repeating units,        of residues of a branching monomer having 3 or more functional        groups wherein the functional groups are hydroxyl, carboxyl, or        a combination thereof;

wherein the fibers have a plurality of segments comprising the waternon-dispersible polymers wherein the segments are substantially isolatedfrom each other by the sulfopolyester intervening between the; and

(B) contacting the multicomponent fibers with water to remove thesulfopolyester thereby forming microdenier fibers.

The water non-dispersible polymers may be biodistintegratable asdetermined by DIN Standard 54900 and/or biodegradable as determined byASTM Standard Method, D6340-98. The multicomponent fiber also may beused to prepare a fibrous article such as a yarn, fabric, melt-blownweb, spunbonded web, or non-woven fabric and which may comprise one ormore layers of fibers. The fibrous article having multicomponent fibers,in turn, may be contacted with water to produce fibrous articlescontaining microdenier fibers.

Thus, another aspect of the invention is a process for a microdenierfiber web, comprising:

(A) spinning a water dispersible sulfopolyester having a glasstransition temperature (Tg) of at least 57° C. and one or more waternon-dispersible polymers immiscible with the sulfopolyester intomulticomponent fibers, the sulfopolyester comprising:

-   -   (i) about 50 to about 96 mole % of one or more residues of        isophthalic acid or terephthalic acid, based on the total acid        residues;    -   (ii) about 4 to about 30 mole %, based on the total acid        residues, of a residue of sodiosulfoisophthalic acid;    -   (iii) one or more diol residues wherein at least 25 mole %,        based on the total diol residues, is a poly(ethylene glycol)        having a structure

H—(OCH₂—CH₂)_(n)—OH

-   -   wherein n is an integer in the range of 2 to about 500; and    -   (iv) 0 to about 20 mole %, based on the total repeating units,        of residues of a branching monomer having 3 or more functional        groups wherein the functional groups are hydroxyl, carboxyl, or        a combination thereof.

wherein the multicomponent fibers have a plurality of segmentscomprising the water non-dispersible polymers and the segments aresubstantially isolated from each other by the sulfopolyester interveningbetween the segments;

(B) overlapping and collecting the multicomponent fibers of Step A toform a nonwoven web; and

(C) contacting the nonwoven web with water to remove the sulfopolyesterthereby forming a microdenier fiber web.

Our invention also provides a process making a water-dispersible,nonwoven fabric comprising:

(A) heating a water-dispersible polymer composition to a temperatureabove its flow point, wherein the polymer composition comprises

-   -   (i) a sulfopolyester having a glass transition temperature (Tg)        of at least 25° C., the sulfopolyester comprising:        -   (a) residues of one or more dicarboxylic acids;        -   (b) about 4 to about 40 mole %, based on the total repeating            units, of residues of at least one sulfomonomer having 2            functional groups and one or more metal sulfonate groups            attached to an aromatic or cycloaliphatic ring wherein the            functional groups are hydroxyl, carboxyl, or a combination            thereof;        -   (c) one or more diol residues wherein at least 20 mole %,            based on the total diol residues, is a poly(ethylene glycol)            having a structure

H—(OCH2-CH2)n-OH

-   -   -   wherein n is an integer in the range of 2 to about 500;        -   (d) 0 to about 25 mole %, based on the total repeating            units, of residues of a branching monomer having 3 or more            functional groups wherein the functional groups are            hydroxyl, carboxyl, or a combination thereof;

    -   (ii) optionally, a water-dispersible polymer blended with the        sulfopolyester; and

    -   (iii) optionally, a water non-dispersible polymer blended with        the sulfopolyester to form a blend with the proviso that the        blend is an immiscible blend;

wherein the polymer composition contains less than 10 weight % of apigment or filler, based on the total weight of the polymer composition;

(B) melt spinning filaments; and

(C) overlapping and collecting the filaments of Step B to form anonwoven web.

In another aspect of the present invention, there is provided amulticomponent fiber, having a shaped cross section, comprising:

(A) at least one water dispersible sulfopolyester; and

(B) a plurality of microfiber domains comprising one or more waternon-dispersible polymers immiscible with the sulfopolyester, wherein thedomains are substantially isolated from each other by the sulfopolyesterintervening between the domains;

wherein the water dispersible sulfopolyesters exhibits a melt viscosityof less than about 12,000 poise measured at 240° C. at a strain rate of1 rad/sec, and wherein the sulfopolyester comprises less than about 25mole of residues of at least one sulfomonomer, based on the total molesof diacid or diol residues.

In another aspect of the present invention, there is provided amulticomponent extrudate having a shaped cross section, comprising:

(A) at least one water dispersible sulfopolyester; and

(B) a plurality of domains comprising one or more water non-dispersiblepolymers immiscible with the sulfopolyester, wherein the domains aresubstantially isolated from each other by the sulfopolyester intervening

between the domains, wherein the extrudate is capable of being meltdrawn at a speed of at least about 2000 m/min.

In another aspect of the present invention, there is provided a processfor making a multicomponent fiber having a shaped cross sectioncomprising spinning at least one water dispersible sulfopolyester andone or more water non-dispersible polymers immiscible with thesulfopolyester, wherein the multicomponent fiber has a plurality ofdomains comprising the water non-dispersible polymers and the domainsare substantially isolated from each other by the sulfopolyesterintervening between the domains; wherein the water dispersiblesulfopolyester exhibits a melt viscosity of less than about 12,000 poisemeasured at 240° C. at a strain rate of 1 rad/sec, and wherein thesulfopolyester comprises less than about 25 mole % of residues of atleast one sulfomonomer, based on the total moles of diacid or diolresidues.

In another aspect of the invention, there is provided a process formaking a multicomponent fiber having a shaped cross section comprisingextruding at least one water dispersible sulfopolyester and one or morewater non-dispersible polymers immiscible with the sulfopolyester toproduce a multicomponent extrudate, wherein the multicomponent extrudatehas a plurality of domains comprising the water non-dispersible polymersand the domains are substantially isolated from each other by thesulfopolyester intervening between the domains; and melt drawing themulticomponent extrudate at a speed of at least about 2000 m/min toproduce the multicomponent fiber.

In another aspect, the present invention provides a process forproducing microdenier fibers comprising:

(A) spinning at least one water dispersible sulfopolyester and one ormore water non-dispersible polymers immiscible with the waterdispersible sulfopolyester into multicomponent fibers, wherein themulticomponent fibers have a plurality of domains comprising the waternon-dispersible polymers wherein the domains are substantially isolatedfrom each other by the sulfopolyester intervening between the domains;wherein the water dispersible sulfopolyester exhibits a melt viscosityof less than about 12,000 poise measured at 240° C. at a strain rate of1 rad/sec, and wherein the sulfopolyester comprises less than about 25mole % of residues of at least one sulfomonomer, based on the totalmoles of diacid or diol residues; and

(B) contacting the multicomponent fibers with water to remove the waterdispersible sulfopolyester thereby forming microdenier fibers of thewater non-dispersible polymer(s).

In another aspect, the present invention provides a process forproducing microdenier fibers comprising:

(A) extruding at least one water dispersible sulfopolyester and one ormore water non-dispersible polymers immiscible with the waterdispersible sulfopolyester to produce multicomponent extrudates, whereinthe multicomponent extrudates have a plurality of domains comprising thewater non-dispersible polymers wherein the domains are substantiallyisolated from each other by the sulfopolyester intervening between thedomains;

(B) melt drawing the multicomponent extrudates at a speed of at leastabout 2000 m/min to form multicomponent fibers; and

(C) contacting the multicomponent fibers with water to remove the waterdispersible sulfopolyester thereby forming microdenier fibers of thewater non-dispersible polymer(s).

In another aspect of this invention, a process is provided for making amicrodenier fiber web comprising:

(A) spinning at least one water dispersible sulfopolyester and one ormore water non-dispersible polymers immiscible with the sulfopolyesterinto multicomponent fibers, the multicomponent fibers have a pluralityof domains comprising the water non-dispersible polymers wherein thedomains are substantially isolated from each other by the waterdispersible sulfopolyester intervening between the domains; wherein thewater dispersible sulfopolyester exhibits a melt viscosity of less thanabout 12,000 poise measured at 240° C. at a strain rate of 1 rad/sec,and wherein the sulfopolyester comprising less than about 25 mole % ofresidues of at least one sulfomonomer, based on the total moles ofdiacid or diol residues;

(B) collecting the multicomponent fibers of Step (A) to form a non-wovenweb; and

(C) contacting the non-woven web with water to remove the sulfopolyesterthereby forming a microdenier fiber web.

In another aspect of this invention, a process for making a microdenierfiber web is provided comprising:

(A) extruding at least one water dispersible sulfopolyester and one ormore water non-dispersible polymers immiscible with the sulfopolyesterto a produce multicomponent extrudate, the multicomponent extrudate havea plurality of domains comprising the water non-dispersible polymerswherein the domains are substantially isolated from each other by thesulfopolyester intervening between the domains;

(B) melt drawing the multicomponent extrudates at a speed of at leastabout 2000 m/min to form multicomponent fibers;

(C) collecting the multicomponent fibers of Step (B) to form a non-wovenweb; and

(D) contacting the non-woven web with water to remove the sulfopolyesterthereby forming a microdenier fiber web.

In another embodiment of this invention, a process for producing cutwater non-dispersible polymer microfibers is provided, the processcomprising:

(A) cutting a multicomponent fiber into cut multicomponent fibers;

(B) contacting a fiber-containing feedstock with water to produce afiber mix slurry; wherein the fiber-containing feedstock comprises cutmulticomponent fibers;

(C) heating the fiber mix slurry to produce a heated fiber mix slurry;

(D) optionally, mixing the fiber mix slurry in a shearing zone;

(E) removing at least a portion of the sulfopolyester from the cutmulticomponent fiber to produce a slurry mixture comprising asulfopolyester dispersion and the cut water non-dispersible polymermicrofibers; and

(F) separating the cut water non-dispersible polymer microfibers fromthe slurry mixture.

In another embodiment of this invention, a cut water non-dispersiblepolymer microfiber is provided comprising at least one waternon-dispersible polymer wherein the cut water non-dispersible polymermicrofiber has an equivalent diameter of less than 5 microns and lengthof less than 25 millimeters.

In another embodiment of this invention, a process for producing anonwoven article from the water non-dispersible polymer microfiber isprovided, the process comprising:

(A) providing a water non-dispersible polymer microfiber produced from amulticomponent fiber; and

(B) producing the nonwoven article utilizing a wet-laid process or adry-laid process.

In another embodiment of the invention, a process for producing amicrofiber product stream is provided. The process comprises:

(A) contacting short cut multicomponent fibers having a length of lessthan 25 millimeters with a heated aqueous stream in a fiber opening zoneto remove a portion of the water dispersible sulfopolyester to producean opened microfiber slurry; wherein the short cut multicomponent fiberscomprise at least one water dispersible sulfopolyester and at least onewater non-dispersible synthetic polymer immiscible with the waterdispersible sulfopolyester; wherein the heated aqueous stream is at atemperature of at least 40° C.; wherein the opened microfiber slurrycomprises water, microfiber, and water dispersible sulfopolyester; and

(B) routing the opened microfiber slurry to a primary solid liquidseparation zone to produce the microfiber product stream and a firstmother liquor stream; wherein the first mother liquor stream compriseswater and the water dispersible sulfopolyester.

In another embodiment of the invention, a process for producing amicrofiber product stream is provided. The process comprises:

(A) contacting short cut multicomponent fibers having a length of lessthan 25 millimeters with a heated aqueous stream in a fiber opening zoneto remove a portion of the water dispersible sulfopolyester to producean opened microfiber slurry; wherein the short cut multicomponent fiberscomprise at least one water dispersible sulfopolyester and at least onewater non-dispersible polymer immiscible with the water dispersiblesulfopolyester; wherein the heated aqueous stream is at a temperature ofat least 40° C.; wherein the opened microfiber slurry comprises waternon-dispersible polymer microfiber, water dispersible sulfopolyester,and water; and

(B) routing the opened microfiber slurry to a primary solid liquidseparation zone to produce the microfiber product stream and a firstmother liquor stream; wherein the first mother liquor stream compriseswater and water dispersible sulfopolyester.

In another embodiment of the invention, another process for producing amicrofiber product stream is provided. The process comprises:

(A) contacting short cut multicomponent fibers having a length of lessthan 25 millimeters with a treated aqueous stream in a fiber slurry zoneto produce a short cut multicomponent fiber slurry; wherein the shortcut multicomponent fibers comprise at least one water dispersiblesulfopolyester and at least one water non-dispersible synthetic polymerimmiscible with the water dispersible sulfopolyester; and wherein thetreated aqueous stream is at a temperature of less than 40° C.;

(B) contacting the short cut multicomponent fiber slurry and a heatedaqueous stream in a fiber opening zone to remove a portion of the waterdispersible sulfopolyester to produce an opened microfiber slurry;wherein the opened microfiber slurry comprises water non-dispersiblepolymer microfiber, water dispersible sulfopolyester, and water; and

(C) routing the opened microfiber slurry to a primary solid liquidseparation zone to produce the microfiber product stream and a firstmother liquor stream; wherein the first mother liquor stream compriseswater and the water dispersible sulfopolyester.

In another embodiment of the invention, another process for producing amicrofiber product stream is provided. The process comprises:

(A) contacting short cut multicomponent fibers having a length of lessthan 25 millimeters with a heated aqueous stream in a mix zone toproduce a short cut multicomponent fiber slurry; wherein the short cutmulticomponent fibers comprise at least one water dispersiblesulfopolyester and at least one water non-dispersible polymer immisciblewith the water dispersible sulfopolyester; and wherein the heatedaqueous stream is at a temperature of 40° C. or greater;

(B) routing the short cut multicomponent fiber slurry and optionally, aheated aqueous stream, to a fiber opening zone to remove a portion ofthe water dispersible sulfopolyester to produce an opened microfiberslurry; wherein the opened microfiber slurry comprises waternon-dispersible polymer microfiber, water dispersible sulfopolyester,and water; and

(C) routing the opened microfiber slurry to a primary solid liquidseparation zone to produce the microfiber product stream and a firstmother liquor stream; wherein the first mother liquor stream compriseswater and the water dispersible sulfopolyester.

In another embodiment of the invention, another process for producing amicrofiber product stream is provided. The process comprises:

(A) contacting short cut multicomponent fibers having a length of lessthan 25 millimeters with a treated aqueous stream in a fiber slurry zoneto produce a short cut multicomponent fiber slurry; wherein the shortcut multicomponent fibers comprise at least one water dispersiblesulfopolyester and at least one water non-dispersible synthetic polymerimmiscible with the water dispersible sulfopolyester; and wherein thetreated aqueous stream is at a temperature of less than 40° C.;

(B) contacting the short cut multicomponent fiber slurry with a heatedaqueous stream in a mix zone to produce a heated multicomponent fiberslurry;

(C) routing the heated multicomponent fiber slurry to a fiber openingzone to remove a portion of the water dispersible sulfopolyester toproduce an opened microfiber slurry; and

(D) routing the opened microfiber slurry to a primary solid liquidseparation zone to produce the microfiber product stream and a firstmother liquor stream; wherein the first mother liquor stream compriseswater and the water dispersible sulfopolyester.

In another embodiment of the invention, a process for separating a firstmother liquor stream is provided. The process comprises routing a firstmother liquor stream to a second solid liquid separation zone to producea secondary wet cake stream and a second mother liquor stream; whereinthe second mother liquor stream comprises water and water dispersiblesulfopolyester; wherein the secondary wet cake stream comprises waternon-dispersible polymer microfiber.

In yet another embodiment of the invention, a process for recoveringsulfopolyester is provided. The process comprises:

(A) routing a second mother liquor to a primary concentration zone toproduce a primary polymer concentrate stream and a primary recoveredwater stream; and

(B) optionally, routing the primary recovered water stream to a fiberopening zone.

BRIEF DESCRIPTION OF THE FIGURES

FIGS. 1 a, 1 b, and 1 c are cross-sectional views of threedifferently-configured fibers, particularly illustrating how variousmeasurements relating to the size and shape of the fibers aredetermined.

FIG. 2 illustrates an embodiment of the invention wherein the microfiberproduct stream is produced in a one step opening zone.

FIGS. 3 a and 3 b illustrate an embodiment of the invention wherein themicrofiber product stream is produced in a two step opening zone.

FIG. 4 illustrates an embodiment of the invention wherein the microfiberproduct stream is produced in a three step opening zone.

FIG. 5 illustrates an embodiment of the process for cuttingmulticomponent fibers to produce short cut multicomponent fibers.

FIG. 6 a illustrates an embodiment of the opening zone wherein theopening zone comprises a pipe.

FIG. 6 b illustrates an embodiment of the opening zone wherein theopening zone comprises a continuous stirred tank.

FIG. 6 c illustrates an embodiment of the opening zone wherein theopening zone comprises more than one continuous stirred tanks.

FIGS. 7 a and 7 b illustrate an embodiment of the primary solid liquidseparation zone.

FIG. 8 shows composition of wash recovered from bicomponent fiberopening at 79° C. in Example 36.

FIG. 9 shows composition of wash recovered from bicomponent fiberopening at 74° C. in Example 38.

FIG. 10 shows composition of filtrate recovered from bicomponent fiberopening at 68° C. in Example 39.

FIG. 11 shows composition of filtrate recovered from bicomponent fiberopening at 63° C. in Example 40.

FIG. 12 shows composition of wash recovered from bicomponent fiberopening at 77° C. using water with 200 ppm calcium in ComparativeExample 41.

DETAILED DESCRIPTION

The present invention provides water-dispersible fibers and fibrousarticles that show tensile strength, absorptivity, flexibility, andfabric integrity in the presence of moisture, especially upon exposureto human bodily fluids. The fibers and fibrous articles of our inventiondo not require the presence of oil, wax, or fatty acid finishes or theuse of large amounts (typically 10 weight % or greater) of pigments orfillers to prevent blocking or fusing of the fibers during processing.In addition, the fibrous articles prepared from our novel fibers do notrequire a binder and readily disperse or dissolve in home or publicsewerage systems.

In a general embodiment, our invention provides a water-dispersiblefiber comprising a sulfopolyester having a glass transition temperature(Tg) of at least 25° C., wherein the sulfopolyester comprises:

(A) residues of one or more dicarboxylic acids;

(B) about 4 to about 40 mole %, based on the total repeating units, ofresidues of at least one sulfomonomer having 2 functional groups and oneor more sulfonate groups attached to an aromatic or cycloaliphatic ringwherein the functional groups are hydroxyl, carboxyl, or a combinationthereof;

(C) one or more diol residues wherein at least 25 mole %, based on thetotal diol residues, is a poly(ethylene glycol) having a structure

H—(OCH₂—CH₂)_(n)—OH

wherein n is an integer in the range of 2 to about 500; and 0 to about25 mole %, based on the total repeating units, of residues of abranching monomer having 3 or more functional groups wherein thefunctional groups are hydroxyl, carboxyl, or a combination thereof. Ourfiber may optionally include a water-dispersible polymer blended withthe sulfopolyester and, optionally, a water non-dispersible polymerblended with the sulfopolyester with the proviso that the blend is animmiscible blend. Our fiber contains less than 10 weight % of a pigmentor filler, based on the total weight of the fiber. The present inventionalso includes fibrous articles comprising these fibers and may includepersonal care products such as wipes, gauze, tissue, diapers, adultincontinence briefs, training pants, sanitary napkins, bandages, andsurgical dressings. The fibrous articles may have one or more absorbentlayers of fibers.

The fibers of our invention may be unicomponent fibers, bicomponent ormulticomponent fibers. For example, the fibers of the present inventionmay be prepared by melt spinning a single sulfopolyester orsulfopolyester blend and include staple, monofilament, and multifilamentfibers with a shaped cross-section. In addition, our invention providesmulticomponent fibers, such as described, for example, in U.S. Pat. No.5,916,678, which may be prepared by extruding the sulfopolyester and oneor more water non-dispersible polymers, which are immiscible with thesulfopolyester, separately through a spinneret having a shaped orengineered transverse geometry such as, for example, an“islands-in-the-sea”, sheath-core, side-by-side, ribbon (stripped), orsegmented pie configuration. The sulfopolyester may be later removed bydissolving the interfacial layers or pie segments and leaving thesmaller filaments or microdenier fibers of the water non-dispersiblepolymer(s). These fibers of the water non-dispersible polymer have fibersize much smaller than the multicomponent fiber before removing thesulfopolyester. For example, the sulfopolyester and waternon-dispersible polymers may be fed to a polymer distribution systemwhere the polymers are introduced into a segmented spinneret plate. Thepolymers follow separate paths to the fiber spinneret and are combinedat the spinneret hole which comprises either two concentric circularholes thus providing a sheath-core type fiber, or a circular spinnerethole divided along a diameter into multiple parts to provide a fiberhaving a side-by-side type. Alternatively, the immiscible waterdispersible sulfopolyester and water non-dispersible polymers may beintroduced separately into a spinneret having a plurality of radialchannels to produce a multicomponent fiber having a segmented pie crosssection. Typically, the sulfopolyester will form the “sheath” componentof a sheath core configuration. In fiber cross sections having aplurality of segments, the water non-dispersible segments, typically,are substantially isolated from each other by the sulfopolyester.Alternatively, multicomponent fibers may be formed by melting thesulfopolyester and water non-dispersible polymers in separate extrudersand directing the polymer flows into one spinneret with a plurality ofdistribution flow paths in form of small thin tubes or segments toprovide a fiber having an islands-in-the-sea shaped cross section. Anexample of such a spinneret is described in U.S. Pat. No. 5,366,804. Inthe present invention, typically, the sulfopolyester will form the “sea”component and the water non-dispersible polymer will form the “islands”component.

Unless otherwise indicated, all numbers expressing quantities ofingredients, properties such as molecular weight, reaction conditions,and so forth used in the specification and claims are to be understoodas being modified in all instances by the term “about.” Accordingly,unless indicated to the contrary, the numerical parameters set forth inthe following specification and attached claims are approximations thatmay vary depending upon the desired properties sought to be obtained bythe present invention. At the very least, each numerical parametershould at least be construed in light of the number of reportedsignificant digits and by applying ordinary rounding techniques.Further, the ranges stated in this disclosure and the claims areintended to include the entire range specifically and not just theendpoint(s). For example, a range stated to be 0 to 10 is intended todisclose all whole numbers between 0 and 10 such as, for example 1, 2,3, 4, etc., all fractional numbers between 0 and 10, for example 1.5,2.3, 4.57, 6.1113, etc., and the endpoints 0 and 10. Also, a rangeassociated with chemical substituent groups such as, for example, “C1 toC5 hydrocarbons”, is intended to specifically include and disclose C1and C5 hydrocarbons as well as C2, C3, and C4 hydrocarbons.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contain certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements.

The unicomponent fibers and fibrous articles produced from theunicomponent fibers of the present invention are water-dispersible and,typically, completely disperse at room temperature. Higher watertemperatures can be used to accelerate their dispersibility or rate ofremoval from the nonwoven or multicomponent fiber. The term“water-dispersible”, as used herein with respect to unicomponent fibersand fibrous articles prepared from unicomponent fibers, is intended tobe synonymous with the terms “water-dissipatable”,“water-disintegratable”, “water-dissolvable”, “water-dispellable”,“water soluble”, water-removable”, “hydrosoluble”, and“hydrodispersible” and is intended to mean that the fiber or fibrousarticle is therein or therethrough dispersed or dissolved by the actionof water. The terms “dispersed”, “dispersible”, “dissipate”, or“dissipatable” mean that, using a sufficient amount of deionized water(e.g., 100:1 water:fiber by weight) to form a loose suspension or slurryof the fibers or fibrous article, at a temperature of about 60° C., andwithin a time period of up to 5 days, the fiber or fibrous articledissolves, disintegrates, or separates into a plurality of incoherentpieces or particles distributed more or less throughout the medium suchthat no recognizable filaments are recoverable from the medium uponremoval of the water, for example, by filtration or evaporation. Thus,“water-dispersible”, as used herein, is not intended to include thesimple disintegration of an assembly of entangled or bound, butotherwise water insoluble or nondispersible, fibers wherein the fiberassembly simply breaks apart in water to produce a slurry of fibers inwater which could be recovered by removal of the water. In the contextof this invention, all of these terms refer to the activity of water ora mixture of water and a water-miscible cosolvent on the sulfopolyestersdescribed herein. Examples of such water-miscible cosolvents includesalcohols, ketones, glycol ethers, esters and the like. It is intendedfor this terminology to include conditions where the sulfopolyester isdissolved to form a true solution as well as those where thesulfopolyester is dispersed within the aqueous medium. Often, due to thestatistical nature of sulfopolyester compositions, it is possible tohave a soluble fraction and a dispersed fraction when a singlesulfopolyester sample is placed in an aqueous medium.

Similarly, the term “water-dispersible”, as used herein in reference tothe sulfopolyester as one component of a multicomponent fiber or fibrousarticle, also is intended to be synonymous with the terms“water-dissipatable”, “water-disintegratable”, “water-dissolvable”,“water-dispellable”, “water soluble”, “water-removable”, “hydrosoluble”,and “hydrodispersible” and is intended to mean that the sulfopolyestercomponent is sufficiently removed from the multicomponent fiber and isdispersed or dissolved by the action of water to enable the release andseparation of the water non-dispersible fibers contained therein. Theterms “dispersed”, “dispersible”, “dissipate”, or “dissipatable” meanthat, using a sufficient amount of deionized water (e.g., 100:1water:fiber by weight) to form a loose suspension or slurry of thefibers or fibrous article, at a temperature of about 60° C., and withina time period of up to 5 days, sulfopolyester component dissolves,disintegrates, or separates from the multicomponent fiber, leavingbehind a plurality of microdenier fibers from the water non-dispersiblesegments.

The term “segment” or “domain” or “zone” when used to describe theshaped cross section of a multicomponent fiber refers to the area withinthe cross section comprising the water non-dispersible polymers wherethese domains or segments are substantially isolated from each other bythe water-dispersible sulfopolyester intervening between the segments ordomains. The term “substantially isolated”, as used herein, is intendedto mean that the segments or domains are set apart from each other topermit the segments domains to form individual fibers upon removal ofthe sulfopolyester. Segments or domains or zones can be of similar sizeand shape or varying size and shape. Again, segments or domains or zonescan be arranged in any configuration. These segments or domains or zonesare “substantially continuous” along the length of the multicomponentextrudate or fiber. The term “substantially continuous” means continuousalong at least 10 cm length of the multicomponent fiber. These segments,domains, or zones of the multicomponent fiber produce waternon-dispersible polymer microfibers when the water dispersiblesulfopolyester is removed.

As stated within this disclosure, the shaped cross section of amulticomponent fiber can, for example, be in the form of a sheath core,islands-in-the sea, segmented pie, hollow segmented pie; off-centeredsegmented pie, side-by-side, ribbon (stripped) etc.

The water-dispersible fiber of the present invention is prepared frompolyesters or, more specifically sulfopolyesters, comprisingdicarboxylic acid monomer residues, sulfomonomer residues, diol monomerresidues, and repeating units. The sulfomonomer may be a dicarboxylicacid, a diol, or hydroxycarboxylic acid. Thus, the term “monomerresidue”, as used herein, means a residue of a dicarboxylic acid, adiol, or a hydroxycarboxylic acid. A “repeating unit”, as used herein,means an organic structure having 2 monomer residues bonded through acarbonyloxy group. The sulfopolyesters of the present invention containsubstantially equal molar proportions of acid residues (100 mole %) anddiol residues (100 mole %) which react in substantially equalproportions such that the total moles of repeating units is equal to 100mole %. The mole % ages provided in the present disclosure, therefore,may be based on the total moles of acid residues, the total moles ofdiol residues, or the total moles of repeating units. For example, asulfopolyester containing 30 mole % of a sulfomonomer, which may be adicarboxylic acid, a diol, or hydroxycarboxylic acid, based on the totalrepeating units, means that the sulfopolyester contains 30 mole %sulfomonomer out of a total of 100 mole % repeating units. Thus, thereare 30 moles of sulfomonomer residues among every 100 moles of repeatingunits. Similarly, a sulfopolyester containing 30 mole % of adicarboxylic acid sulfomonomer, based on the total acid residues, meansthe sulfopolyester contains 30 mole % sulfomonomer out of a total of 100mole % acid residues. Thus, in this latter case, there are 30 moles ofsulfomonomer residues among every 100 moles of acid residues.

The sulfopolyesters described herein have an inherent viscosity,abbreviated hereinafter as “Ih.V.”, of at least about 0.1 dL/g,preferably about 0.2 to 0.3 dL/g, and most preferably greater than about0.3 dL/g, measured in a 60/40 parts by weight solution ofphenol/tetrachloroethane solvent at 25° C. and at a concentration ofabout 0.5 g of sulfopolyester in 100 mL of solvent. The term“polyester”, as used herein, encompasses both “homopolyesters” and“copolyesters” and means a synthetic polymer prepared by thepolycondensation of difunctional carboxylic acids with difunctionalhydroxyl compound. As used herein, the term “sulfopolyester” means anypolyester comprising a sulfomonomer. Typically the difunctionalcarboxylic acid is a dicarboxylic acid and the difunctional hydroxylcompound is a dihydric alcohol such as, for example glycols and diols.Alternatively, the difunctional carboxylic acid may be a hydroxycarboxylic acid such as, for example, p-hydroxybenzoic acid, and thedifunctional hydroxyl compound may be a aromatic nucleus bearing 2hydroxy substituents such as, for example, hydroquinone. The term“residue”, as used herein, means any organic structure incorporated intothe polymer through a polycondensation reaction involving thecorresponding monomer. Thus, the dicarboxylic acid residue may bederived from a dicarboxylic acid monomer or its associated acid halides,esters, salts, anhydrides, or mixtures thereof. As used herein,therefore, the term dicarboxylic acid is intended to includedicarboxylic acids and any derivative of a dicarboxylic acid, includingits associated acid halides, esters, half-esters, salts, half-salts,anhydrides, mixed anhydrides, or mixtures thereof, useful in apolycondensation process with a diol to make a high molecular weightpolyester.

The sulfopolyester of the present invention includes one or moredicarboxylic acid residues. Depending on the type and concentration ofthe sulfomonomer, the dicarboxylic acid residue may comprise from about60 to about 100 mole % of the acid residues. Other examples ofconcentration ranges of dicarboxylic acid residues are from about 60mole % to about 95 mole %, and about 70 mole % to about 95 mole %.Examples of dicarboxylic acids that may be used include aliphaticdicarboxylic acids, alicyclic dicarboxylic acids, aromatic dicarboxylicacids, or mixtures of two or more of these acids. Thus, suitabledicarboxylic acids include, but are not limited to, succinic; glutaric;adipic; azelaic; sebacic; fumaric; maleic; itaconic;1,3-cyclohexanedicarboxylic; 1,4-cyclohexanedicarboxylic; diglycolic;2,5-norbornanedicarboxylic; phthalic; terephthalic;1,4-naphthalenedicarboxylic; 2,5-naphthalenedicarboxylic; diphenic;4,4′-oxydibenzoic; 4,4′-sulfonyldibenzoic; and isophthalic. Thepreferred dicarboxylic acid residues are isophthalic, terephthalic, and1,4-cyclohexanedicarboxylic acids, or if diesters are used, dimethylterephthalate, dimethyl isophthalate, anddimethyl-1,4-cyclohexanedicarboxylate with the residues of isophthalicand terephthalic acid being especially preferred. Although thedicarboxylic acid methyl ester is the most preferred embodiment, it isalso acceptable to include higher order alkyl esters, such as ethyl,propyl, isopropyl, butyl, and so forth. In addition, aromatic esters,particularly phenyl, also may be employed.

The sulfopolyester includes about 4 to about 40 mole %, based on thetotal repeating units, of residues of at least one sulfomonomer having 2functional groups and one or more sulfonate groups attached to anaromatic or cycloaliphatic ring wherein the functional groups arehydroxyl, carboxyl, or a combination thereof. Additional examples ofconcentration ranges for the sulfomonomer residues are about 4 to about35 mole %, about 8 to about 30 mole %, and about 8 to about 25 mole %,based on the total repeating units. The sulfomonomer may be adicarboxylic acid or ester thereof containing a sulfonate group, a diolcontaining a sulfonate group, or a hydroxy acid containing a sulfonategroup. The term “sulfonate” refers to a salt of a sulfonic acid havingthe structure “—SO₃M” wherein M is the cation of the sulfonate salt. Thecation of the sulfonate salt may be a metal ion such as Li⁺, Na⁺, K⁺,Mg⁺⁺, Ca⁺⁺, Ni⁺⁺, Fe⁺⁺, and the like. Alternatively, the cation of thesulfonate salt may be non-metallic such as a nitrogenous base asdescribed, for example, in U.S. Pat. No. 4,304,901. Nitrogen-basedcations are derived from nitrogen-containing bases, which may bealiphatic, cycloaliphatic, or aromatic compounds. Examples of suchnitrogen containing bases include ammonia, dimethylethanolamine,diethanolamine, triethanolamine, pyridine, morpholine, and piperidine.Because monomers containing the nitrogen-based sulfonate salts typicallyare not thermally stable at conditions required to make the polymers inthe melt, the method of this invention for preparing sulfopolyesterscontaining nitrogen-based sulfonate salt groups is to disperse,dissipate, or dissolve the polymer containing the required amount ofsulfonate group in the form of its alkali metal salt in water and thenexchange the alkali metal cation for a nitrogen-based cation.

When a monovalent alkali metal ion is used as the cation of thesulfonate salt, the resulting sulfopolyester is completely dispersiblein water with the rate of dispersion dependent on the content ofsulfomonomer in the polymer, temperature of the water, surfacearea/thickness of the sulfopolyester, and so forth. When a divalentmetal ion is used, the resulting sulfopolyesters are not readilydispersed by cold water but are more easily dispersed by hot water.Utilization of more than one counterion within a single polymercomposition is possible and may offer a means to tailor or fine-tune thewater-responsivity of the resulting article of manufacture. Examples ofsulfomonomers residues include monomer residues where the sulfonate saltgroup is attached to an aromatic acid nucleus, such as, for example,benzene; naphthalene; diphenyl; oxydiphenyl; sulfonyldiphenyl; andmethylenediphenyl or cycloaliphatic rings, such as, for example,cyclohexyl; cyclopentyl; cyclobutyl; cycloheptyl; and cyclooctyl. Otherexamples of sulfomonomer residues which may be used in the presentinvention are the metal sulfonate salt of sulfophthalic acid,sulfoterephthalic acid, sulfoisophthalic acid, or combinations thereof.Other examples of sulfomonomers which may be used are 5-sodiosulfoisophthalic acid and esters thereof. If the sulfomonomer residueis from 5-sodiosulfoisophthalic acid, typical sulfomonomer concentrationranges are about 4 to about 35 mole %, about 8 to about 30 mole %, andabout 8 to 25 mole %, based on the total moles of acid residues.

The sulfomonomers used in the preparation of the sulfopolyesters areknown compounds and may be prepared using methods well known in the art.For example, sulfomonomers in which the sulfonate group is attached toan aromatic ring may be prepared by sulfonating the aromatic compoundwith oleum to obtain the corresponding sulfonic acid and followed byreaction with a metal oxide or base, for example, sodium acetate, toprepare the sulfonate salt. Procedures for preparation of varioussulfomonomers are described, for example, in U.S. Pat. Nos. 3,779,993;3,018,272; and 3,528,947.

It is also possible to prepare the polyester using, for example, asodium sulfonate salt, and ion-exchange methods to replace the sodiumwith a different ion, such as zinc, when the polymer is in the dispersedform. This type of ion exchange procedure is generally superior topreparing the polymer with divalent salts insofar as the sodium saltsare usually more soluble in the polymer reactant melt-phase.

The sulfopolyester includes one or more diol residues which may includealiphatic, cycloaliphatic, and aralkyl glycols. The cycloaliphaticdiols, for example, 1,3- and 1,4-cyclohexanedimethanol, may be presentas their pure cis or trans isomers or as a mixture of cis and transisomers. As used herein, the term “diol” is synonymous with the term“glycol” and means any dihydric alcohol. Examples of diols include, butare not limited to, ethylene glycol; diethylene glycol; triethyleneglycol; polyethylene glycols; 1,3-propanediol;2,4-dimethyl-2-ethylhexane-1,3-diol; 2,2-dimethyl-1,3-propanediol;2-ethyl-2-butyl-1,3-propanediol; 2-ethyl-2-isobutyl-1,3-propanediol;1,3-butanediol; 1,4-butanediol; 1,5-pentanediol; 1,6-hexanediol;2,2,4-trimethyl-1,6-hexanediol; thiodiethanol;1,2-cyclohexanedimethanol; 1,3-cyclohexanedimethanol;1,4-cyclohexanedimethanol; 2,2,4,4-tetramethyl-1,3-cyclobutanediol;p-xylylenediol, or combinations of one or more of these glycols.

The diol residues may include from about 25 mole % to about 100 mole %,based on the total diol residues, of residue of a poly(ethylene glycol)having a structure

H—(OCH₂—CH₂)_(n)—OH

wherein n is an integer in the range of 2 to about 500. Non-limitingexamples of lower molecular weight polyethylene glycols, e.g., wherein nis from 2 to 6, are diethylene glycol, triethylene glycol, andtetraethylene glycol. Of these lower molecular weight glycols,diethylene and triethylene glycol are most preferred. Higher molecularweight polyethylene glycols (abbreviated herein as “PEG”), wherein n isfrom 7 to about 500, include the commercially available products knownunder the designation CARBOWAX®, a product of Dow Chemical Company(formerly Union Carbide). Typically, PEGs are used in combination withother diols such as, for example, diethylene glycol or ethylene glycol.Based on the values of n, which range from greater than 6 to 500, themolecular weight may range from greater than 300 to about 22,000 g/mol.The molecular weight and the mole % are inversely proportional to eachother; specifically, as the molecular weight is increased, the mole %will be decreased in order to achieve a designated degree ofhydrophilicity. For example, it is illustrative of this concept toconsider that a PEG having a molecular weight of 1000 may constitute upto 10 mole % of the total diol, while a PEG having a molecular weight of10,000 would typically be incorporated at a level of less than 1 mole %of the total diol.

Certain dimer, trimer, and tetramer diols may be formed in situ due toside reactions that may be controlled by varying the process conditions.For example, varying amounts of diethylene, triethylene, andtetraethylene glycols may be formed from ethylene glycol from anacid-catalyzed dehydration reaction which occurs readily when thepolycondensation reaction is carried out under acidic conditions. Thepresence of buffer solutions, well-known to those skilled in the art,may be added to the reaction mixture to retard these side reactions.Additional compositional latitude is possible, however, if the buffer isomitted and the dimerization, trimerization, and tetramerizationreactions are allowed to proceed.

The sulfopolyester of the present invention may include from 0 to about25 mole %, based on the total repeating units, of residues of abranching monomer having 3 or more functional groups wherein thefunctional groups are hydroxyl, carboxyl, or a combination thereof.Non-limiting examples of branching monomers are 1,1,1-trimethylolpropane, 1,1,1-trimethylolethane, glycerin, pentaerythritol, erythritol,threitol, dipentaerythritol, sorbitol, trimellitic anhydride,pyromellitic dianhydride, dimethylol propionic acid, or combinationsthereof. Further examples of branching monomer concentration ranges arefrom 0 to about 20 mole % and from 0 to about 10 mole %. The presence ofa branching monomer may result in a number of possible benefits to thesulfopolyester of the present invention, including but not limited to,the ability to tailor rheological, solubility, and tensile properties.For example, at a constant molecular weight, a branched sulfopolyester,compared to a linear analog, will also have a greater concentration ofend groups that may facilitate post-polymerization crosslinkingreactions. At high concentrations of branching agent, however, thesulfopolyester may be prone to gelation.

The sulfopolyester used for the fiber of the present invention has aglass transition temperature, abbreviated herein as “Tg”, of at least25° C. as measured on the dry polymer using standard techniques, such asdifferential scanning calorimetry (“DSC”), well known to persons skilledin the art. The Tg measurements of the sulfopolyesters of the presentinvention are conducted using a “dry polymer”, that is, a polymer samplein which adventitious or absorbed water is driven off by heating topolymer to a temperature of about 200° C. and allowing the sample toreturn to room temperature. Typically, the sulfopolyester is dried inthe DSC apparatus by conducting a first thermal scan in which the sampleis heated to a temperature above the water vaporization temperature,holding the sample at that temperature until the vaporization of thewater absorbed in the polymer is complete (as indicated by an a large,broad endotherm), cooling the sample to room temperature, and thenconducting a second thermal scan to obtain the Tg measurement. Furtherexamples of glass transition temperatures exhibited by thesulfopolyester are at least 30° C., at least 35° C., at least 40° C., atleast 50° C., at least 60° C., at least 65° C., at least 80° C., and atleast 90° C. Although other Tg's are possible, typical glass transitiontemperatures of the dry sulfopolyesters our invention are about 30° C.,about 48° C., about 55° C., about 65° C., about 70° C., about 75° C.,about 85° C., and about 90° C.

Our novel fibers may consist essentially of or, consist of, thesulfopolyesters described hereinabove. In another embodiment, however,the sulfopolyesters of this invention may be a single polyester or maybe blended with one or more supplemental polymers to modify theproperties of the resulting fiber. The supplemental polymer may or maynot be water-dispersible depending on the application and may bemiscible or immiscible with the sulfopolyester. If the supplementalpolymer is water non-dispersible, it is preferred that the blend withthe sulfopolyester is immiscible. The term “miscible”, as used herein,is intended to mean that the blend has a single, homogeneous amorphousphase as indicated by a single composition-dependent Tg. For example, afirst polymer that is miscible with second polymer may be used to“plasticize” the second polymer as illustrated, for example, in U.S.Pat. No. 6,211,309. By contrast, the term “immiscible”, as used herein,denotes a blend that shows at least 2, randomly mixed, phases andexhibits more than one Tg. Some polymers may be immiscible and yetcompatible with the sulfopolyester. A further general description ofmiscible and immiscible polymer blends and the various analyticaltechniques for their characterization may be found in Polymer BlendsVolumes 1 and 2, Edited by D. R. Paul and C. B. Bucknall, 2000, JohnWiley & Sons, Inc.

Non-limiting examples of water-dispersible polymers that may be blendedwith the sulfopolyester are polymethacrylic acid, polyvinyl pyrrolidone,polyethylene-acrylic acid copolymers, polyvinyl methyl ether, polyvinylalcohol, polyethylene oxide, hydroxy propyl cellulose, hydroxypropylmethyl cellulose, methyl cellulose, ethyl hydroxyethyl cellulose,isopropyl cellulose, methyl ether starch, polyacrylamides, poly(N-vinylcaprolactam), polyethyl oxazoline, poly(2-isopropyl-2-oxazoline),polyvinyl methyl oxazolidone, water-dispersible sulfopolyesters,polyvinyl methyl oxazolidimone, poly(2,4-dimethyl-6-triazinylethylene),and ethylene oxide-propylene oxide copolymers. Examples of polymerswhich are water non-dispersible that may be blended with thesulfopolyester include, but are not limited to, polyolefins, such ashomo- and copolymers of polyethylene and polypropylene; poly(ethyleneterephthalate); poly(butylene terephthalate); and polyamides, such asnylon-6; polylactides; caprolactone; Eastar Bio® (poly(tetramethyleneadipate-co-terephthalate), a product of Eastman Chemical Company);polycarbonate; polyurethane; and polyvinyl chloride.

According to our invention, blends of more than one sulfopolyester maybe used to tailor the end-use properties of the resulting fiber orfibrous article, for example, a nonwoven fabric or web. The blends ofone or more sulfopolyesters will have Tg's of at least 25° C. for thewater-dispersible, unicomponent fibers and at least 57° C. for themulticomponent fibers. Thus, blending may also be exploited to alter theprocessing characteristics of a sulfopolyester to facilitate thefabrication of a nonwoven. In another example, an immiscible blend ofpolypropylene and sulfopolyester may provide a conventional nonwoven webthat will break apart and completely disperse in water as truesolubility is not needed. In this latter example, the desiredperformance is related to maintaining the physical properties of thepolypropylene while the sulfopolyester is only a spectator during theactual use of the product or, alternatively, the sulfopolyester isfugitive and is removed before the final form of the product isutilized.

The sulfopolyester and supplemental polymer may be blended in batch,semicontinuous, or continuous processes. Small scale batches may bereadily prepared in any high-intensity mixing devices well-known tothose skilled in the art, such as Banbury mixers, prior to melt-spinningfibers. The components may also be blended in solution in an appropriatesolvent. The melt blending method includes blending the sulfopolyesterand supplemental polymer at a temperature sufficient to melt thepolymers. The blend may be cooled and pelletized for further use or themelt blend can be melt spun directly from this molten blend into fiberform. The term “melt” as used herein includes, but is not limited to,merely softening the polyester. For melt mixing methods generally knownin the polymers art, see Mixing and Compounding of Polymers (I.Manas-Zloczower & Z. Tadmor editors, Carl Hanser Verlag Publisher, 1994,New York, N.Y.).

Our invention also provides a water-dispersible fiber comprising asulfopolyester having a glass transition temperature (Tg) of at least25° C., wherein the sulfopolyester comprises:

(A) about 50 to about 96 mole % of one or more residues of isophthalicacid or terephthalic acid, based on the total acid residues;

(B) about 4 to about 30 mole %, based on the total acid residues, of aresidue of sod iosulfoisophthalic acid;

(C) one or more diol residues wherein at least 25 mole %, based on thetotal diol residues, is a poly(ethylene glycol) having a structure

H—(OCH₂—CH₂)_(n)—OH

wherein n is an integer in the range of 2 to about 500; (iv) 0 to about20 mole %, based on the total repeating units, of residues of abranching monomer having 3 or more functional groups wherein thefunctional groups are hydroxyl, carboxyl, or a combination thereof. Asdescribed hereinabove, the fiber may optionally include a firstwater-dispersible polymer blended with the sulfopolyester; and,optionally, a water non-dispersible polymer blended with thesulfopolyester such that the blend is an immiscible blend. Our fiber maycontain less than 10 weight % of a pigment or filler, less than 8 weight%, or less than 6 weight % based on the total weight of the fiber. Thefirst water-dispersible polymer is as described hereinabove. Thesulfopolyester should have a glass transition temperature (Tg) of atleast 25° C., but may have, for example, a Tg of about 35° C., about 48°C., about 55° C., about 65° C., about 70° C., about 75° C., about 85°C., and about 90° C. The sulfopolyester may contain other concentrationsof isophthalic acid residues, for example, about 60 to about 95 mole %,and about 75 to about 95 mole %. Further examples of isophthalic acidresidue concentrations ranges are about 70 to about 85 mole %, about 85to about 95 mole % and about 90 to about 95 mole %. The sulfopolyesteralso may comprise about 25 to about 95 mole % of the residues ofdiethylene glycol. Further examples of diethylene glycol residueconcentration ranges include about 50 to about 95 mole %, about 70 toabout 95 mole %, and about 75 to about 95 mole %. The sulfopolyesteralso may include the residues of ethylene glycol and/or1,4-cyclohexanedimethanol, abbreviated herein as “CHDM”. Typicalconcentration ranges of CHDM residues are about 10 to about 75 mole %,about 25 to about 65 mole %, and about 40 to about 60 mole %. Typicalconcentration ranges of ethylene glycol residues are about 10 to about75 mole %, about 25 to about 65 mole %, and about 40 to about 60 mole %.In another embodiment, the sulfopolyester comprises is about 75 to about96 mole % of the residues of isophthalic acid and about 25 to about 95mole % of the residues of diethylene glycol.

The sulfopolyesters of the instant invention are readily prepared fromthe appropriate dicarboxylic acids, esters, anhydrides, or salts,sulfomonomer, and the appropriate diol or diol mixtures using typicalpolycondensation reaction conditions. They may be made by continuous,semi-continuous, and batch modes of operation and may utilize a varietyof reactor types. Examples of suitable reactor types include, but arenot limited to, stirred tank, continuous stirred tank, slurry, tubular,wiped-film, falling film, or extrusion reactors. The term “continuous”as used herein means a process wherein reactants are introduced andproducts withdrawn simultaneously in an uninterrupted manner. By“continuous” it is meant that the process is substantially or completelycontinuous in operation and is to be contrasted with a “batch” process.“Continuous” is not meant in any way to prohibit normal interruptions inthe continuity of the process due to, for example, start-up, reactormaintenance, or scheduled shut down periods. The term “batch” process asused herein means a process wherein all the reactants are added to thereactor and then processed according to a predetermined course ofreaction during which no material is fed or removed into the reactor.The term “semicontinuous” means a process where some of the reactantsare charged at the beginning of the process and the remaining reactantsare fed continuously as the reaction progresses. Alternatively, asemicontinuous process may also include a process similar to a batchprocess in which all the reactants are added at the beginning of theprocess except that one or more of the products are removed continuouslyas the reaction progresses. The process is operated advantageously as acontinuous process for economic reasons and to produce superiorcoloration of the polymer as the sulfopolyester may deteriorate inappearance if allowed to reside in a reactor at an elevated temperaturefor too long a duration.

The sulfopolyesters of the present invention are prepared by proceduresknown to persons skilled in the art. The sulfomonomer is most oftenadded directly to the reaction mixture from which the polymer is made,although other processes are known and may also be employed, forexample, as described in U.S. Pat. Nos. 3,018,272, 3,075,952, and3,033,822. The reaction of the sulfomonomer, diol component and thedicarboxylic acid component may be carried out using conventionalpolyester polymerization conditions. For example, when preparing thesulfopolyesters by means of an ester interchange reaction, i.e., fromthe ester form of the dicarboxylic acid components, the reaction processmay comprise two steps. In the first step, the diol component and thedicarboxylic acid component, such as, for example, dimethylisophthalate, are reacted at elevated temperatures, typically, about150° C. to about 250° C. for about 0.5 to about 8 hours at pressuresranging from about 0.0 kPa gauge to about 414 kPa gauge (60 pounds persquare inch, “psig”). Preferably, the temperature for the esterinterchange reaction ranges from about 180° C. to about 230° C. forabout 1 to about 4 hours while the preferred pressure ranges from about103 kPa gauge (15 psig) to about 276 kPa gauge (40 psig). Thereafter,the reaction product is heated under higher temperatures and underreduced pressure to form sulfopolyester with the elimination of diol,which is readily volatilized under these conditions and removed from thesystem. This second step, or polycondensation step, is continued underhigher vacuum and a temperature which generally ranges from about 230°C. to about 350° C., preferably about 250° C. to about 310° C. and mostpreferably about 260° C. to about 290° C. for about 0.1 to about 6hours, or preferably, for about 0.2 to about 2 hours, until a polymerhaving the desired degree of polymerization, as determined by inherentviscosity, is obtained. The polycondensation step may be conducted underreduced pressure which ranges from about 53 kPa (400 torr) to about0.013 kPa (0.1 torr). Stirring or appropriate conditions are used inboth stages to ensure adequate heat transfer and surface renewal of thereaction mixture. The reactions of both stages are facilitated byappropriate catalysts such as, for example, alkoxy titanium compounds,alkali metal hydroxides and alcoholates, salts of organic carboxylicacids, alkyl tin compounds, metal oxides, and the like. A three-stagemanufacturing procedure, similar to that described in U.S. Pat. No.5,290,631, may also be used, particularly when a mixed monomer feed ofacids and esters is employed.

To ensure that the reaction of the diol component and dicarboxylic acidcomponent by an ester interchange reaction mechanism is driven tocompletion, it is preferred to employ about 1.05 to about 2.5 moles ofdiol component to one mole dicarboxylic acid component. Persons of skillin the art will understand, however, that the ratio of diol component todicarboxylic acid component is generally determined by the design of thereactor in which the reaction process occurs.

In the preparation of sulfopolyester by direct esterification, i.e.,from the acid form of the dicarboxylic acid component, sulfopolyestersare produced by reacting the dicarboxylic acid or a mixture ofdicarboxylic acids with the diol component or a mixture of diolcomponents. The reaction is conducted at a pressure of from about 7 kPagauge (1 psig) to about 1379 kPa gauge (200 psig), preferably less than689 kPa (100 psig) to produce a low molecular weight, linear or branchedsulfopolyester product having an average degree of polymerization offrom about 1.4 to about 10. The temperatures employed during the directesterification reaction typically range from about 180° C. to about 280°C., more preferably ranging from about 220° C. to about 270° C. This lowmolecular weight polymer may then be polymerized by a polycondensationreaction.

The water dispersible, multicomponent, and short cut fibers and fibrousarticles made therefrom also may contain other conventional additivesand ingredients which do not deleteriously affect their end use. Forexample, additives such as fillers, surface friction modifiers, lightand heat stabilizers, extrusion aids, antistatic agents, colorants,dyes, pigments, fluorescent brighteners, antimicrobials,anticounterfeiting markers, hydrophobic and hydrophilic enhancers,viscosity modifiers, slip agents, tougheners, adhesion promoters, andthe like may be used.

The fibers and fibrous articles of our invention do not require thepresence of additives such as, for example, pigments, fillers, oils,waxes, or fatty acid finishes, to prevent blocking or fusing of thefibers during processing. The terms “blocking or fusing”, as usedherein, is understood to mean that the fibers or fibrous articles sticktogether or fuse into a mass such that the fiber cannot be processed orused for its intended purpose. Blocking and fusing can occur duringprocessing of the fiber or fibrous article or during storage over aperiod of days or weeks and is exacerbated under hot, humid conditions.

In one embodiment of the invention, the fibers and fibrous articles willcontain less than 10 weight % of such anti-blocking additives, based onthe total weight of the fiber or fibrous article. For example, thefibers and fibrous articles may contain less than 10 weight % of apigment or filler. In other examples, the fibers and fibrous articlesmay contain less than 9 weight %, less than 5 weight %, less than 3weight %, less than 1 weight %, and 0 weight % of a pigment or filler,based on the total weight of the fiber. Colorants, sometimes referred toas toners, may be added to impart a desired neutral hue and/orbrightness to the sulfopolyester. When colored fibers are desired,pigments or colorants may be included in the sulfopolyester reactionmixture during the reaction of the diol monomer and the dicarboxylicacid monomer or they may be melt blended with the preformedsulfopolyester. A preferred method of including colorants is to use acolorant having thermally stable organic colored compounds havingreactive groups such that the colorant is copolymerized and incorporatedinto the sulfopolyester to improve its hue. For example, colorants suchas dyes possessing reactive hydroxyl and/or carboxyl groups, including,but not limited to, blue and red substituted anthraquinones, may becopolymerized into the polymer chain. When dyes are employed ascolorants, they may be added to the copolyester reaction process afteran ester interchange or direct esterification reaction.

For the purposes of this invention, the term “fiber” refers to apolymeric body of high aspect ratio capable of being formed into two orthree dimensional articles such as woven or nonwoven fabrics. In thecontext of the present invention, the term “fiber” is synonymous with“fibers” and intended to mean one or more fibers. The fibers of ourinvention may be unicomponent fibers, bicomponent, or multicomponentfibers. The term “unicomponent fiber”, as used herein, is intended tomean a fiber prepared by melt spinning a single sulfopolyester, blendsof one or more sulfopolyesters, or blends of one or more sulfopolyesterswith one or more additional polymers and includes staple, monofilament,and multifilament fibers. “Unicomponent” is intended to be synonymouswith the term “monocomponent” and includes “biconstituent” or“multiconstituent” fibers, and refers to fibers which have been formedfrom at least two polymers extruded from the same extruder as a blend.Unicomponent or biconstituent fibers do not have the various polymercomponents arranged in relatively constantly positioned distinct zonesacross the cross-sectional area of the fiber and the various polymersare usually not continuous along the entire length of the fiber, insteadusually forming fibrils or protofibrils which start and end at random.Thus, the term “unicomponent” is not intended to exclude fibers formedfrom a polymer or blends of one or more polymers to which small amountsof additives may be added for coloration, anti-static properties,lubrication, hydrophilicity, etc.

By contrast, the term “multicomponent fiber”, as used herein, intendedto mean a fiber prepared by melting the two or more fiber formingpolymers in separate extruders and by directing the resulting multiplepolymer flows into one spinneret with a plurality of distribution flowpaths but spun together to form one fiber. Multicomponent fibers arealso sometimes referred to as conjugate or bicomponent fibers. Thepolymers are arranged in substantially constantly positioned distinctsegments or zones across the cross-section of the conjugate fibers andextend continuously along the length of the conjugate fibers. Theconfiguration of such a multicomponent fiber may be, for example, asheath/core arrangement wherein one polymer is surrounded by another ormay be a side by side arrangement, a ribbon or stripped arrangement, apie arrangement or an “islands-in-the-sea” arrangement. For example, amulticomponent fiber may be prepared by extruding the sulfopolyester andone or more water non-dispersible polymers separately through aspinneret having a shaped or engineered transverse geometry such as, forexample, an “islands-in-the-sea” or segmented pie configuration.Multicomponent fibers, typically, are staple, monofilament ormultifilament fibers that have a shaped or round cross-section. Mostfiber forms are heatset. The fiber may include the various antioxidants,pigments, and additives as described herein.

Monofilament fibers generally range in size from about 15 to about 8000denier per filament (abbreviated herein as “d/f”). Our novel fiberstypically will have d/f values in the range of about 40 to about 5000.Monofilaments may be in the form of unicomponent or multicomponentfibers. The multifilament fibers of our invention will preferably rangein size from about 1.5 micrometers for melt blown webs, about 0.5 toabout 50 d/f for staple fibers, and up to about 5000 d/f formonofilament fibers. Multifilament fibers may also be used as crimped oruncrimped yarns and tows. Fibers used in melt blown web and melt spunfabrics may be produced in microdenier sizes. The term “microdenier”, asused herein, is intended to mean a d/f value of 1 d/f or less. Forexample, the microdenier fibers of the instant invention typically haved/f values of 1 or less, 0.5 or less, or 0.1 or less. Nanofibers canalso be produced by electrostatic spinning.

As noted hereinabove, the sulfopolyesters also are advantageous for thepreparation of bicomponent and multicomponent fibers having a shapedcross section. We have discovered that sulfopolyesters or blends ofsulfopolyesters having a glass transition temperature (Tg) of at least57° C. are particularly useful for multicomponent fibers to preventblocking and fusing of the fiber during spinning and take up. Thus, ourinvention provides a multicomponent fiber having shaped cross section,comprising:

(A) a water dispersible sulfopolyester having a glass transitiontemperature (Tg) of at least 57° C., the sulfopolyester comprising:

-   -   (i) residues of one or more dicarboxylic acids;    -   (ii) about 4 to about 40 mole %, based on the total repeating        units, of residues of at least one sulfomonomer having 2        functional groups and one or more sulfonate groups attached to        an aromatic or cycloaliphatic ring wherein the functional groups        are hydroxyl, carboxyl, or a combination thereof;    -   (iii) one or more diol residues wherein at least 25 mole %,        based on the total diol residues, is a poly(ethylene glycol)        having a structure

H—(OCH₂—CH₂)_(n)—OH

-   -   wherein n is an integer in the range of 2 to about 500; and    -   (iv) 0 to about 25 mole %, based on the total repeating units,        of residues of a branching monomer having 3 or more functional        groups wherein the functional groups are hydroxyl, carboxyl, or        a combination thereof; and

(B) a plurality of segments comprising one or more water non-dispersiblepolymers immiscible with the sulfopolyester, wherein the segments aresubstantially isolated from each other by the sulfopolyester interveningbetween the segments;

Optionally, wherein the fiber has an islands-in-the-sea or segmented piecross section and contains less than 10 weight % of a pigment or filler,based on the total weight of the fiber.

The dicarboxylic acids, diols, sulfopolyester, sulfomonomers, andbranching monomers residues are as described previously for otherembodiments of the invention. For multicomponent fibers, it isadvantageous that the sulfopolyester have a Tg of at least 57° C.Further examples of glass transition temperatures that may be exhibitedby the sulfopolyester or sulfopolyester blend of our multicomponentfiber are at least 60° C., at least 65° C., at least 70° C., at least75° C., at least 80° C., at least 85° C., and at least 90° C. Further,to obtain a sulfopolyester with a Tg of at least 57° C., blends of oneor more sulfopolyesters may be used in varying proportions to obtain asulfopolyester blend having the desired Tg. The Tg of a sulfopolyesterblend may be calculated by using a weighted average of the Tg's of thesulfopolyester components. For example, sulfopolyester having a Tg of48° C. may be blended in a 25:75 wt:wt ratio with another sulfopolyesterhaving Tg of 65° C. to give a sulfopolyester blend having a Tg ofapproximately 61° C.

In another embodiment of the invention, the water dispersiblesulfopolyester component of the multicomponent fiber presents propertieswhich allow at least one of the following:

(A) the multicomponent fibers to be spun to a desired low denier,

(B) the sulfopolyester in these mulficomponent fibers is resistant toremoval during hydroentangling of a web formed from the fibers but isefficiently removed at elevated temperatures after hydroentanglement,and

(C) the multicomponent fibers are heat settable to yield a stable,strong fabric. Surprising and unexpected results were achieved infurtherance of these objectives using a sulfopolyester having a certainmelt viscosity and level of sulfomonomer residues.

Therefore, in another embodiment of the invention, a multicomponentfiber is provided having a shaped cross section comprising:

(A) at least one water dispersible sulfopolyester; and

(B) a plurality of domains comprising one or more water non-dispersiblepolymers immiscible with the sulfopolyester, wherein the domains aresubstantially isolated from each other by the sulfopolyester interveningbetween the domains,

optionally, wherein the fiber has an as-spun denier of less than about 6denier per filament;

wherein the water dispersible sulfopolyesters exhibits a melt viscosityof less than about 12,000 poise measured at 240° C. at a strain rate of1 rad/sec, and

wherein the sulfopolyester comprises less than about 25 mole % ofresidues of at least one sulfomonomer, based on the total moles ofdiacid or diol residues.

The sulfopolyester utilized in these multicomponent fibers has a meltviscosity of generally less than about 12,000 poise. In otherembodiments, the melt viscosity of the sulfopolyester is less than about10,000 poise, less than about 6,000, or less than about 4,000 poisemeasured at 240° C. and 1 rad/sec shear rate. In another aspect, thesulfopolyester exhibits a melt viscosity of between about 1,000 to about12,000 poise, between about 2,000 to about 6,000 poise, or between about2,500 to about 4,000 poise measured at 240° C. and 1 rad/sec shear rate.Prior to determining the viscosity, the samples are dried at 60° C. in avacuum oven for 2 days. The melt viscosity is measured on rheometerusing a 25 mm diameter parallel-plate geometry at 1 mm gap setting. Adynamic frequency sweep is run at a strain rate range of 1 to 400rad/sec and 10% strain amplitude. The viscosity is then measured at 240°C. and strain rate of 1 rad/sec.

The level of sulfomonomer residues in the sulfopolyester polymers foruse in accordance with this aspect of the present invention is generallyless than about 25 mole % or less than about 20 mole %, reported as apercentage of the total diacid or diol residues in the sulfopolyester.In other embodiments, this level is between about 4 to about 20 mole %,between about 5 to about 12 mole %, or between about 7 to about 10 mole%. Sulfomonomers for use with the invention preferably have 2 functionalgroups and one or more sulfonate groups attached to an aromatic orcycloaliphatic ring wherein the functional groups are hydroxyl,carboxyl, or a combination thereof. In one embodiment, asodiosulfo-isophthalic acid monomer is utilized.

In addition to the sulfomonomer described previously, the sulfopolyestercan comprise residues of one or more dicarboxylic acids, one or morediol residues wherein at least 25 mole %, based on the total diolresidues, is a poly(ethylene glycol) having a structure

H—(OCH₂—CH₂)_(n)—OH

wherein n is an integer in the range of 2 to about 500, and 0 to about20 mole %, based on the total repeating units, of residues of abranching monomer having 3 or more functional groups wherein thefunctional groups are hydroxyl, carboxyl, or a combination thereof.

In another embodiment, the sulfopolyester comprises from about 80-96mole % dicarboxylic acid residues, from about 4 to about 20 mole %sulfomonomer residues, and 100 mole % diol residues (there being a totalmole % of 200%, i.e., 100 mole % diacid and 100 mole % diol). Morespecifically, the dicarboxylic portion of the sulfopolyester comprisesbetween about 60-80 mole % terephthalic acid, about 0-30 mole %isophthalic acid, and about 4-20 mole % 5-sodiosulfoisophthalic acid(5-SSIPA). The diol portion comprises from about 0-50 mole % diethyleneglycol and from about 50-100 mole % ethylene glycol. An exemplaryformulation according to this embodiment of the invention is set forthsubsequently.

Approximate Mole % (based on total moles of diol or diacid residues)Terephthalic acid 71 Isophthalic acid 20 5-SSIPA 9 Diethylene glycol 35Ethylene glycol 65

The water non-dispersible component of the multicomponent fiber maycomprise any of those water non-dispersible polymers described herein.Spinning of the fiber may also occur according to any method describedherein. However, the improved rheological properties of multicomponentfibers in accordance with this aspect of the invention provide forenhanced drawings speeds. When the sulfopolyester and waternon-dispersible polymer are extruded to produce multicomponentextrudates, the multicomponent extrudate is capable of being melt drawnto produce the multicomponent fiber, using any of the methods disclosedherein, at a speed of at least about 2000 m/min, more preferably atleast about 3000 m/min, even more preferably at least about 4000 m/min,and most preferably at least about 4500 m/min. Although not intending tobe bound by theory, melt drawing of the multicomponent extrudates atthese speeds results in at least some oriented crystallinity in thewater non-dispersible component of the multicomponent fiber. Thisoriented crystallinity can increase the dimensional stability ofnon-woven materials made from the multicomponent fibers duringsubsequent processing.

Another advantage of the multicomponent extrudate is that it can be meltdrawn to a multicomponent fiber having an as-spun denier of less than 6deniers per filament. Other ranges of multicomponent fiber sizes includean as-spun denier of less than 4 deniers per filament and less than 2.5deniers per filament.

Therefore, in another embodiment of the invention, a multicomponentextrudate having a shaped cross section, comprising:

(A) at least one water dispersible sulfopolyester; and

(B) a plurality of domains comprising one or more water non-dispersiblepolymers immiscible with the sulfopolyester, wherein the domains aresubstantially isolated from each other by the sulfopolyester interveningbetween the domains,

wherein the extrudate is capable of being melt drawn at a speed of atleast about 2000 m/min.

The multicomponent fiber comprises a plurality of segments or domains ofone or more water non-dispersible polymers immiscible with thesulfopolyester in which the segments or domains are substantiallyisolated from each other by the sulfopolyester intervening between thesegments or domains. The term “substantially isolated”, as used herein,is intended to mean that the segments or domains are set apart from eachother to permit the segments domains to form individual fibers uponremoval of the sulfopolyester. For example, the segments or domains maybe touching each others as in, for example, a segmented pieconfiguration but can be split apart by impact or when thesulfopolyester is removed.

The ratio by weight of the sulfopolyester to water non-dispersiblepolymer component in the multicomponent fiber of the invention isgenerally in the range of about 60:40 to about 2:98 or, in anotherexample, in the range of about 50:50 to about 5:95. Typically, thesulfopolyester comprises 50% by weight or less of the total weight ofthe multicomponent fiber.

The segments or domains of multicomponent fiber may comprise one of morewater non-dispersible polymers. Examples of water non-dispersiblepolymers which may be used in segments of the multicomponent fiberinclude, but are not limited to, polyolefins, polyesters, polyamides,polylactides, polycaprolactone, polycarbonate, polyurethane, celluloseester, and polyvinyl chloride. For example, the water non-dispersiblepolymer may be polyester such as poly(ethylene)terephthalate,poly(butylene)terephthalate,poly(cyclohexylene)cyclohexanedicarboxylate,poly(cyclohexylene)terephthalate, poly(trimethylene)terephthalate, andthe like. In another example, the water non-dispersible polymer can bebiodistintegratable as determined by DIN Standard 54900 and/orbiodegradable as determined by ASTM Standard Method, D6340-98. Examplesof biodegradable polyesters and polyester blends are disclosed in U.S.Pat. Nos. 5,599,858; 5,580,911; 5,446,079; and 5,559,171. The term“biodegradable”, as used herein in reference to the waternon-dispersible polymers of the present invention, is understood to meanthat the polymers are degraded under environmental influences such as,for example, in a composting environment, in an appropriate anddemonstrable time span as defined, for example, by ASTM Standard Method,D6340-98, entitled “Standard Test Methods for Determining AerobicBiodegradation of Radiolabeled Plastic Materials in an Aqueous orCompost Environment”. The water non-dispersible polymers of the presentinvention also may be “biodisintegratable”, meaning that the polymersare easily fragmented in a composting environment as defined, forexample, by DIN Standard 54900. For example, the biodegradable polymeris initially reduced in molecular weight in the environment by theaction of heat, water, air, microbes and other factors. This reductionin molecular weight results in a loss of physical properties (tenacity)and often in fiber breakage. Once the molecular weight of the polymer issufficiently low, the monomers and oligomers are then assimilated by themicrobes. In an aerobic environment, these monomers or oligomers areultimately oxidized to CO₂, H₂O, and new cell biomass. In an anaerobicenvironment, the monomers or oligomers are ultimately converted to CO₂,H₂, acetate, methane, and cell biomass.

For example, water non-dispersible polymer may be an aliphatic-aromaticpolyester, abbreviated herein as “AAPS”. The term “aliphatic-aromaticpolyester”, as used herein, means a polyester comprising a mixture ofresidues from aliphatic or cycloaliphatic dicarboxylic acids or diolsand aromatic dicarboxylic acids or diols. The term “non-aromatic”, asused herein with respect to the dicarboxylic acid and diol monomers ofthe present invention, means that carboxyl or hydroxyl groups of themonomer are not connected through an aromatic nucleus. For example,adipic acid contains no aromatic nucleus in its backbone, i.e., thechain of carbon atoms connecting the carboxylic acid groups, thus is“non-aromatic”. By contrast, the term “aromatic” means the dicarboxylicacid or diol contains an aromatic nucleus in the backbone such as, forexample, terephthalic acid or 2,6-naphthalene dicarboxylic acid.“Non-aromatic”, therefore, is intended to include both aliphatic andcycloaliphatic structures such as, for example, diols and dicarboxylicacids, which contain as a backbone a straight or branched chain orcyclic arrangement of the constituent carbon atoms which may besaturated or paraffinic in nature, unsaturated, i.e., containingnon-aromatic carbon-carbon double bonds, or acetylenic, i.e., containingcarbon-carbon triple bonds. Thus, in the context of the description andthe claims of the present invention, non-aromatic is intended to includelinear and branched, chain structures (referred to herein as“aliphatic”) and cyclic structures (referred to herein as “alicyclic” or“cycloaliphatic”). The term “non-aromatic”, however, is not intended toexclude any aromatic substituents which may be attached to the backboneof an aliphatic or cycloaliphatic diol or dicarboxylic acid. In thepresent invention, the difunctional carboxylic acid typically is aaliphatic dicarboxylic acid such as, for example, adipic acid, or anaromatic dicarboxylic acid such as, for example, terephthalic acid. Thedifunctional hydroxyl compound may be cycloaliphatic diol such as, forexample, 1,4-cyclohexanedimethanol, a linear or branched aliphatic diolsuch as, for example, 1,4-butanediol, or an aromatic diol such as, forexample, hydroquinone.

The AAPE may be a linear or branched random copolyester and/or chainextended copolyester comprising diol residues which comprise theresidues of one or more substituted or unsubstituted, linear orbranched, diols selected from aliphatic diols containing 2 to about 8carbon atoms, polyalkylene ether glycols containing 2 to 8 carbon atoms,and cycloaliphatic diols containing about 4 to about 12 carbon atoms.The substituted diols, typically, will comprise 1 to about 4substituents independently selected from halo, C₆-C₁₀ aryl, and C₁-C₄alkoxy. Examples of diols which may be used include, but are not limitedto, ethylene glycol, diethylene glycol, propylene glycol,1,3-propanediol, 2,2-dimethyl-1,3-propanediol, 1,3-butanediol,1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, polyethylene glycol,diethylene glycol, 2,2,4-trimethyl-1,6-hexanediol, thiodiethanol,1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol,2,2,4,4-tetramethyl-1,3-cyclobutanediol, triethylene glycol, andtetraethylene glycol with the preferred diols comprising one or morediols selected from 1,4-butanediol; 1,3-propanediol; ethylene glycol;1,6-hexanediol; diethylene glycol; or 1,4-cyclohexanedimethanol. TheAAPE also comprises diacid residues which contain about 35 to about 99mole %, based on the total moles of diacid residues, of the residues ofone or more substituted or unsubstituted, linear or branched,non-aromatic dicarboxylic acids selected from aliphatic dicarboxylicacids containing 2 to about 12 carbon atoms and cycloaliphatic acidscontaining about 5 to about 10 carbon atoms. The substitutednon-aromatic dicarboxylic acids will typically contain 1 to about 4substituents selected from halo, C₆-C₁₀ aryl, and C₁-C₄ alkoxy.Non-limiting examples of non-aromatic diacids include malonic, succinic,glutaric, adipic, pimelic, azelaic, sebacic, fumaric, 2,2-dimethylglutaric, suberic, 1,3-cyclopentanedicarboxylic,1,4-cyclohexanedicarboxylic, 1,3-cyclohexanedicarboxylic, diglycolic,itaconic, maleic, and 2,5-norbornanedicarboxylic. In addition to thenon-aromatic dicarboxylic acids, the AAPE comprises about 1 to about 65mole %, based on the total moles of diacid residues, of the residues ofone or more substituted or unsubstituted aromatic dicarboxylic acidscontaining 6 to about 10 carbon atoms. In the case where substitutedaromatic dicarboxylic acids are used, they will typically contain 1 toabout 4 substituents selected from halo, C₆-C₁₀ aryl, and C₁-C₄ alkoxy.Non-limiting examples of aromatic dicarboxylic acids which may be usedin the AAPE of our invention are terephthalic acid, isophthalic acid,salts of 5-sulfoisophthalic acid, and 2,6-naphthalenedicarboxylic acid.More preferably, the non-aromatic dicarboxylic acid will comprise adipicacid, the aromatic dicarboxylic acid will comprise terephthalic acid,and the diol will comprise 1,4-butanediol.

Other possible compositions for the AAPE's of our invention are thoseprepared from the following diols and dicarboxylic acids (orpolyester-forming equivalents thereof such as diesters) in the followingmole % ages, based on 100 mole % of a diacid component and 100 mole % ofa diol component:

-   -   (1) glutaric acid (about 30 to about 75%); terephthalic acid        (about 25 to about 70%); 1,4-butanediol (about 90 to 100%); and        modifying diol (0 about 10%);    -   (2) succinic acid (about 30 to about 95%); terephthalic acid        (about 5 to about 70%); 1,4-butanediol (about 90 to 100%); and        modifying diol (0 to about 10%); and    -   (3) adipic acid (about 30 to about 75%); terephthalic acid        (about 25 to about 70%); 1,4-butanediol (about 90 to 100%); and        modifying diol (0 to about 10%).

The modifying diol preferably is selected from1,4-cyclohexanedimethanol, triethylene glycol, polyethylene glycol andneopentyl glycol. The most preferred AAPE's are linear, branched orchain extended copolyesters comprising about 50 to about 60 mole %adipic acid residues, about 40 to about 50 mole % terephthalic acidresidues, and at least 95 mole % 1,4-butanediol residues. Even morepreferably, the adipic acid residues comprise about 55 to about 60 mole%, the terephthalic acid residues comprise about 40 to about 45 mole %,and the diol residues comprise about 95 mole % 1,4-butanediol residues.Such compositions are commercially available under the trademark EASTARBIO® copolyester from Eastman Chemical Company, Kingsport, Tenn., andunder the trademark ECOFLEX® from BASF Corporation.

Additional, specific examples of preferred AAPE's include apoly(tetramethylene glutarate-co-terephthalate) containing (a) 50 molepercent glutaric acid residues, 50 mole percent terephthalic acidresidues, and 100 mole percent 1,4-butanediol residues, (b) 60 molepercent glutaric acid residues, 40 mole percent terephthalic acidresidues, and 100 mole percent 1,4-butanediol residues or (c) 40 molepercent glutaric acid residues, 60 mole percent terephthalic acidresidues, and 100 mole percent 1,4-butanediol residues; apoly(tetramethylene succinate-co-terephthalate) containing (a) 85 molepercent succinic acid residues, 15 mole percent terephthalic acidresidues, and 100 mole percent 1,4-butanediol residues or (b) 70 molepercent succinic acid residues, 30 mole percent terephthalic acidresidues, and 100 mole percent 1,4-butanediol residues; a poly(ethylenesuccinate-co-terephthalate) containing 70 mole percent succinic acidresidues, 30 mole percent terephthalic acid residues, and 100 molepercent ethylene glycol residues; and a poly(tetramethyleneadipate-co-terephthalate) containing (a) 85 mole percent adipic acidresidues, 15 mole percent terephthalic acid residues, and 100 molepercent 1,4-butanediol residues; or (b) 55 mole percent adipic acidresidues, 45 mole percent terephthalic acid residues, and 100 molepercent 1,4-butanediol residues.

The AAPE preferably comprises from about 10 to about 1,000 repeatingunits and preferably, from about 15 to about 600 repeating units. TheAAPE may have an inherent viscosity of about 0.4 to about 2.0 dL/g, ormore preferably about 0.7 to about 1.6 dL/g, as measured at atemperature of 25° C. using a concentration of 0.5 gram copolyester in100 ml of a 60/40 by weight solution of phenol/tetrachloroethane.

The AAPE, optionally, may contain the residues of a branching agent. Themole % age ranges for the branching agent are from about 0 to about 2mole %, preferably about 0.1 to about 1 mole %, and most preferablyabout 0.1 to about 0.5 mole % based on the total moles of diacid or diolresidues (depending on whether the branching agent contains carboxyl orhydroxyl groups). The branching agent preferably has a weight averagemolecular weight of about 50 to about 5000, more preferably about 92 toabout 3000, and a functionality of about 3 to about 6. The branchingagent, for example, may be the esterified residue of a polyol having 3to 6 hydroxyl groups, a polycarboxylic acid having 3 or 4 carboxylgroups (or ester-forming equivalent groups) or a hydroxy acid having atotal of 3 to 6 hydroxyl and carboxyl groups. In addition, the AAPE maybe branched by the addition of a peroxide during reactive extrusion.

Each segment of the water non-dispersible polymer may be different fromothers in fineness and may be arranged in any shaped or engineeredcross-sectional geometry known to persons skilled in the art. Forexample, the sulfopolyester and a water non-dispersible polymer may beused to prepare a bicomponent fiber having an engineered geometry suchas, for example, a side-by-side, “islands-in-the-sea”, segmented pie,sheath/core, ribbon (stripped), or other configurations known to personsskilled in the art. Other multicomponent configurations are alsopossible. Subsequent removal of a side, the “sea”, or a portion of the“pie” can result in very fine fibers. The process of preparingbicomponent fibers also is well known to persons skilled in the art. Ina bicomponent fiber, the sulfopolyester fibers of this invention may bepresent in amounts of about 10 to about 90 weight % and will generallybe used in the sheath portion of sheath/core fibers. Typically, when awater-insoluble or water non-dispersible polymer is used, the resultingbicomponent or multicomponent fiber is not completely water-dispersible.Side by side combinations with significant differences in thermalshrinkage can be utilized for the development of a spiral crimp. Ifcrimping is desired, a saw tooth or stuffer box crimp is generallysuitable for many applications. If the second polymer component is inthe core of a sheath/core configuration, such a core optionally may bestabilized.

The sulfopolyesters are particularly useful for fibers having an“islands-in-the-sea” or “segmented pie” cross section as they onlyrequires neutral or slightly acidic (i.e., “soft” water) to disperse, ascompared to the caustic-containing solutions that are sometimes requiredto remove other water dispersible polymers from multicomponent fibers.The term “soft water” as used in this disclosure means that the waterhas up to 5 grains per gallon as CaCO₃ (1 grain of CaCO₃ per gallon isequivalent to 17.1 ppm).

Another aspect of our invention is a multicomponent fiber, comprising:

(A) a water dispersible sulfopolyester having a glass transitiontemperature (Tg) of at least 57° C., the sulfopolyester comprising:

-   -   (i) about 50 to about 96 mole % of one or more residues of        isophthalic acid or terephthalic acid, based on the total acid        residues;    -   (ii) about 4 to about 30 mole %, based on the total acid        residues, of a residue of sodiosulfoisophthalic acid;    -   (iii) one or more diol residues wherein at least 25 mole %,        based on the total diol residues, is a poly(ethylene glycol)        having a structure

H—(OCH₂—CH₂)_(n)—OH

-   -   wherein n is an integer in the range of 2 to about 500;    -   (iv) 0 to about 20 mole %, based on the total repeating units,        of residues of a branching monomer having 3 or more functional        groups wherein the functional groups are hydroxyl, carboxyl, or        a combination thereof; and

(B) a plurality of segments comprising one or more water non-dispersiblepolymers immiscible with the sulfopolyester, wherein the segments aresubstantially isolated from each other by the sulfopolyester interveningbetween the segments.

In one embodiment, the multicomponent fiber has an islands-in-the-sea orsegmented pie cross section and contains less than 10 weight % of apigment or filler, based on the total weight of the fiber.

The dicarboxylic acids, diols, sulfopolyester, sulfomonomers, branchingmonomers residues, and water non-dispersible polymers are as describedpreviously. For multicomponent fibers, it is advantageous thatsulfopolyester have a Tg of at least 57° C. The sulfopolyester may be asingle sulfopolyester or a blend of one or more sulfopolyester polymers.Further examples of glass transition temperatures that may be exhibitedby the sulfopolyester or sulfopolyester blends are at least 65° C., atleast 70° C., at least 75° C., at least 85° C., and at least 90° C. Forexample, the sulfopolyester may comprise about 75 to about 96 mole % ofone or more residues of isophthalic acid or terephthalic acid and about25 to about 95 mole % of a residue of diethylene glycol. As describedhereinabove, examples of the water non-dispersible polymers arepolyolefins, polyesters, polyamides, polylactides, polycaprolactones,polycarbonates, polyurethanes, cellulose esters, and polyvinylchlorides. In addition, the water non-dispersible polymer may bebiodegradable or biodisintegratable. For example, the waternon-dispersible polymer may be an aliphatic-aromatic polyester asdescribed previously.

Our novel multicomponent fiber may be prepared by any number of methodsknown to persons skilled in the art. The present invention thus providesa process for a multicomponent fiber having a shaped cross sectioncomprising: spinning a water dispersible sulfopolyester having a glasstransition temperature (Tg) of at least 57° C. and one or more waternon-dispersible polymers immiscible with the sulfopolyester into afiber, the sulfopolyester comprising:

-   -   (A) residues of one or more dicarboxylic acids;    -   (B) about 4 to about 40 mole %, based on the total repeating        units, of residues of at least one sulfomonomer having 2        functional groups and one or more sulfonate groups attached to        an aromatic or cycloaliphatic ring wherein the functional groups        are hydroxyl, carboxyl, or a combination thereof;    -   (C) one or more diol residues wherein at least 25 mole %, based        on the total diol residues, is a poly(ethylene glycol) having a        structure

H—(OCH₂—CH₂)_(n)—OH

-   -   wherein n is an integer in the range of 2 to about 500; and    -   (D) 0 to about 25 mole %, based on the total repeating units, of        residues of a branching monomer having 3 or more functional        groups wherein the functional groups are hydroxyl, carboxyl, or        a combination thereof;

wherein the fiber has a plurality of segments comprising the waternon-dispersible polymers and the segments are substantially isolatedfrom each other by the sulfopolyester intervening between the segments.In one embodiment, the fiber contains less than 10 weight % of a pigmentor filler, based on the total weight of the fiber. For example, themulticomponent fiber may be prepared by melting the sulfopolyester andone or more water non-dispersible polymers in separate extruders anddirecting the individual polymer flows into one spinneret or extrusiondie with a plurality of distribution flow paths such that the waternon-dispersible polymer component form small segments or thin strandswhich are substantially isolated from each other by the interveningsulfopolyester. The cross section of such a fiber may be, for example, asegmented pie arrangement or an islands-in-the-sea arrangement. Inanother example, the sulfopolyester and one or more waternon-dispersible polymers are separately fed to the spinneret orificesand then extruded in sheath-core form in which the water non-dispersiblepolymer forms a “core” that is substantially enclosed by thesulfopolyester “sheath” polymer. In the case of such concentric fibers,the orifice supplying the “core” polymer is in the center of thespinning orifice outlet and flow conditions of core polymer fluid arestrictly controlled to maintain the concentricity of both componentswhen spinning. Modifications in spinneret orifices enable differentshapes of core and/or sheath to be obtained within the fibercross-section. In yet another example, a multicomponent fiber having aside-by-side cross section or configuration may be produced (1) bycoextruding the water dispersible sulfopolyester and waternon-dispersible polymer through orifices separately and converging theseparate polymer streams at substantially the same speed to mergeside-by-side as a combined stream below the face of the spinneret; or(2) by feeding the two polymer streams separately through orifices,which converge at the surface of the spinneret, at substantially thesame speed to merge side-by-side as a combined stream at the surface ofthe spinneret. In both cases, the velocity of each polymer stream, atthe point of merge, is determined by its metering pump speed, the numberof orifices, and the size of the orifice.

The dicarboxylic acids, diols, sulfopolyester, sulfomonomers, branchingmonomers residues, and water non-dispersible polymers are as describedpreviously. The sulfopolyester has a glass transition temperature of atleast 57° C. Further examples of glass transition temperatures that maybe exhibited by the sulfopolyester or sulfopolyester blend are at least65° C., at least 70° C., at least 75° C., at least 85° C., and at least90° C. In one example, the sulfopolyester may comprise about 50 to about96 mole % of one or more residues of isophthalic acid or terephthalicacid, based on the total acid residues; and about 4 to about 30 mole %,based on the total acid residues, of a residue of sod iosulfoisophthalicacid; and 0 to about 20 mole %, based on the total repeating units, ofresidues of a branching monomer having 3 or more functional groupswherein the functional groups are hydroxyl, carboxyl, or a combinationthereof. In another example, the sulfopolyester may comprise about 75 toabout 96 mole % of one or more residues of isophthalic acid orterephthalic acid and about 25 to about 95 mole % of a residue ofdiethylene glycol. As described hereinabove, examples of the waternon-dispersible polymers are polyolefins, polyesters, polyamides,polylactides, polycaprolactone, polycarbonate, polyurethane, andpolyvinyl chloride. In addition, the water non-dispersible polymer maybe biodegradable or biodisintegratable. For example, the waternon-dispersible polymer may be an aliphatic-aromatic polyester asdescribed previously. Examples of shaped cross sections include, but arenot limited to, islands-in-the-sea, side-by-side, sheath-core, segmentedpie, or ribbon (stripped) configurations.

In another embodiment of the invention, a process for making amulticomponent fiber having a shaped cross section is providedcomprising: spinning at least one water dispersible sulfopolyester andone or more water non-dispersible polymers immiscible with thesulfopolyester to produce a multicomponent fiber, wherein themulticomponent fiber has a plurality of domains comprising the waternon-dispersible polymers and the domains are substantially isolated fromeach other by the sulfopolyester intervening between the domains;wherein the water dispersible sulfopolyester exhibits a melt viscosityof less than about 12,000 poise measured at 240° C. at a strain rate of1 rad/sec, and wherein the sulfopolyester comprising less than about 25mole % of residues of at least one sulfomonomer, based on the totalmoles of diacid or diol residues. In another embodiment, themulticomponent fiber has an as-spun denier of less than about 6 denierper filament.

The sulfopolyester utilized in these multicomponent fiber and the waternon-dispersible polymers were discussed previously in this disclosure.

In another embodiment of this invention, a process for making amulticomponent fiber having a shaped cross section is providedcomprising:

(A) extruding at least one water dispersible sulfopolyester and one ormore water non-dispersible polymers immiscible with the sulfopolyesterto produce a multicomponent extrudate, wherein the multicomponentextrudate has a plurality of domains comprising the waternon-dispersible polymers and the domains are substantially isolated fromeach other by the sulfopolyester intervening between the domains; and

(B) melt drawing the multicomponent extrudate at a speed of at leastabout 2000 m/min to produce the multicomponent fiber.

It is also a feature of this embodiment of the invention that theprocess includes the step of melt drawing the multicomponent extrudateat a speed of at least about 2000 m/min, at least about 3000 m/min, orat least 4500 m/min.

Typically, upon exiting the spinneret, the fibers are quenched with across flow of air whereupon the fibers solidify. Various finishes andsizes may be applied to the fiber at this stage. The cooled fibers,typically, are subsequently drawn and wound up on a take up spool. Otheradditives may be incorporated in the finish in effective amounts likeemulsifiers, antistatics, antimicrobials, antifoams, lubricants,thermostabilizers, UV stabilizers, and the like.

Optionally, the drawn fibers may be textured and wound-up to form abulky continuous filament. This one-step technique is known in the artas spin-draw-texturing. Other embodiments include flat filament(non-textured) yarns, or cut staple fiber, either crimped or uncrimped.

The sulfopolyester may be later removed by dissolving the interfaciallayers or pie segments and leaving the smaller filaments or microdenierfibers of the water non-dispersible polymer(s). Our invention thusprovides a process for microdenier fibers comprising:

(A) spinning a water dispersible sulfopolyester having a glasstransition temperature (Tg) of at least 57° C. and one or more waternon-dispersible polymers immiscible with the sulfopolyester intomulticomponent fibers, the sulfopolyester comprising:

-   -   (i) about 50 to about 96 mole % of one or more residues of        isophthalic acid or terephthalic acid, based on the total acid        residues;    -   (ii) about 4 to about 30 mole %, based on the total acid        residues, of a residue of sodiosulfoisophthalic acid;    -   (iii) one or more diol residues wherein at least 25 mole %,        based on the total diol residues, is a poly(ethylene glycol)        having a structure

H—(OCH₂—CH₂)_(n)—OH

-   -   wherein n is an integer in the range of 2 to about 500; and    -   (iv) 0 to about 20 mole %, based on the total repeating units,        of residues of a branching monomer having 3 or more functional        groups wherein the functional groups are hydroxyl, carboxyl, or        a combination thereof;

wherein the fibers have a plurality of segments comprising the waternon-dispersible polymers wherein the segments are substantially isolatedfrom each other by the sulfopolyester intervening between the segments;and

(B) contacting the multicomponent fibers with water to remove thesulfopolyester thereby forming microdenier fibers.

In another embodiment, the multicomponent fibers contain less than 10weight % of a pigment or filler, based on the total weight of thefibers.

Typically, the multicomponent fiber is contacted with water at atemperature in a range of about 25° C. to about 100° C. or in a range ofabout 50° C. to about 80° C. for a time period of from about 10 to about600 seconds whereby the sulfopolyester is dissipated or dissolved. Afterremoval of the sulfopolyester, the remaining water non-dispersiblepolymer microfibers typically will have an average fineness of 1 d/f orless, typically, 0.5 d/f or less, or more typically, 0.1 d/f or less.

Typical applications of these remaining water non-dispersible polymermicrofibers include nonwoven fabrics, such as, for example, artificialleathers, suedes, wipes, and filter media. Filter media produce fromthese microfibers can be utilized to filter air or liquids. Filter mediafor liquids include, but are not limited to, water, bodily fluids,solvents, and hydrocarbons. The ionic nature of sulfopolyesters alsoresults in advantageously poor “solubility” in saline media, such asbody fluids. Such properties are desirable in personal care products andcleaning wipes that are flushable or otherwise disposed in sanitarysewage systems. Selected sulfopolyesters have also been utilized asdispersing agents in dye baths and soil redeposition preventative agentsduring laundry cycles.

In another embodiment of the present invention, a process for makingmicrodenier fibers is provided comprising spinning at least one waterdispersible sulfopolyester and one or more water non-dispersiblepolymers immiscible with the water dispersible sulfopolyester intomulticomponent fibers, wherein the multicomponent fibers have aplurality of domains comprising the water non-dispersible polymerswherein the domains are substantially isolated from each other by thesulfopolyester intervening between the domains; wherein the waterdispersible sulfopolyester exhibits a melt viscosity of less than about12,000 poise measured at 240° C. at a strain rate of 1 rad/sec, andwherein the sulfopolyester comprising less than about 25 mole % ofresidues of at least one sulfomonomer, based on the total moles ofdiacid or diol residues; and contacting the multicomponent fibers withwater to remove the water dispersible sulfopolyester thereby formingmicrodenier fibers. In one embodiment, the multicomponent fiber has anas-spun denier of less than about 6 denier per filament.

In another embodiment of the invention, a process for making microdenierfibers is provided comprising:

(A) extruding at least one water dispersible sulfopolyester and one ormore water non-dispersible polymers immiscible with the waterdispersible sulfopolyester to produce multicomponent extrudates, whereinthe multicomponent extrudates have a plurality of domains comprising thewater non-dispersible polymers wherein the domains are substantiallyisolated from each other by the sulfopolyester intervening between thedomains;

(B) melt drawing the multicomponent extrudates at a speed of at leastabout 2000 m/min to form multicomponent fibers; and

(C) contacting the multicomponent fibers with water to remove the waterdispersible sulfopolyester thereby forming microdenier fibers.

The multicomponent extrudates can be drawn at a speed of at least about2000 m/min, at least about 3000 m/min, or at least 4500 m/min.

Such sulfomonomers and sulfopolyesters suitable for use in accordancewith the invention are described above.

In one embodiment, that the water used to remove the sulfopolyester fromthe multicomponent fibers is above room temperature. In otherembodiments, the water used to remove the sulfopolyester is at leastabout 45° C., at least about 60° C., or at least about 80° C.

In another embodiment of this invention, another process is provided toproduce cut water non-dispersible polymer microfibers. The processcomprises:

(A) cutting a multicomponent fiber into cut multicomponent fibers;

(B) contacting a fiber-containing feedstock with water to produce afiber mix slurry; wherein the fiber-containing feedstock comprises cutmulticomponent fibers;

(C) heating the fiber mix slurry to produce a heated fiber mix slurry;

(D) optionally, mixing the fiber mix slurry in a shearing zone;

(E) removing at least a portion of the sulfopolyester from the cutmulticomponent fiber to produce a slurry mixture comprising asulfopolyester dispersion and the water non-dispersible polymermicrofibers; and

(F) separating the water non-dispersible polymer microfibers from theslurry mixture.

The multicomponent fiber can be cut into any length that can be utilizedto produce nonwoven articles. In one embodiment of the invention, themulticomponent fiber is cut into lengths ranging from about 1 mm toabout 50 mm. In other embodiments, the multicomponent fiber can be cutinto lengths ranging from about 1 mm to about 25 mm, from about 1 mm toabout 20 mm, from about 1 mm to about 15 mm, from about 1 mm to about 10mm, from about 1 mm to about 6 mm, from about 1 mm to about 5 mm, fromabout 1 mm to about 5 mm. In another embodiment, the cut multicomponentfiber is cut into lengths of less than about 25 mm, less than about 20mm, less than about 15 mm, less than about 10 mm, or less than about 5mm.

In another aspect of the invention, the multicomponent fiber can be cutinto a mixture of different lengths.

As used in this disclosure, the term “staple fiber” is used to definefiber cut into lengths of greater than 25 mm to about 50 mm. The term“short-cut fiber” is used to define fiber cut to lengths of about 25 mmor less.

The fiber-containing feedstock can comprise any other type of fiber thatis useful in the production of nonwoven articles. In one embodiment, thefiber-containing feedstock further comprises at least one fiber selectedfrom the group consisting of cellulosic fiber pulp, glass fiber,polyester fibers, nylon fibers, polyolefin fibers, rayon fibers andcellulose ester fibers.

The fiber-containing feedstock is mixed with water to produce a fibermix slurry. Preferably, to facilitate the removal of thewater-dispersible sulfopolyester, the water utilized can be soft wateror deionized water. Soft water has been previously defined in thisdisclosure. In one embodiment of this invention, at least one watersoftening agent may be used to facilitate the removal of thewater-dispersible sulfopolyester from the multicomponent fiber. Anywater softening agent known in the art can be utilized. In oneembodiment, the water softening agent is a chelating agent or calciumion sequestrant. Applicable chelating agents or calcium ion sequestrantsare compounds containing a plurality of carboxylic acid groups permolecule where the carboxylic groups in the molecular structure of thechelating agent are separated by 2 to 6 atoms. Tetrasodium ethylenediamine tetraacetic acid (EDTA) is an example of the most commonchelating agent, containing four carboxylic acid moieties per molecularstructure with a separation of 3 atoms between adjacent carboxylic acidgroups. Poly acrylic acid, sodium salt is an example of a calciumsequestrant containing carboxylic acid groups separated by two atomsbetween carboxylic groups. Sodium salts of maleic acid or succinic acidare examples of the most basic chelating agent compounds. Furtherexamples of applicable chelating agents include compounds which have incommon the presence of multiple carboxylic acid groups in the molecularstructure where the carboxylic acid groups are separated by the requireddistance (2 to 6 atom units) which yield a favorable steric interactionwith di- or multi-valent cations such as calcium which cause thechelating agent to preferentially bind to di- or multi valent cations.Such compounds include, but are not limited to,diethylenetriaminepentaacetic acid;diethylenetriamine-N,N,N′,N′,N″-pentaacetic acid; pentetic acid;N,N-bis(2-(bis-(carboxymethyl)amino)ethylyglycine; diethylenetriaminepentaacetic acid;[[(carboxymethyl)imino]bis(ethylenenitrilo)]-tetra-acetic acid; edeticacid; ethylenedinitrilotetraacetic acid; EDTA, free base; EDTA freeacid; ethylenediamine-N,N,N′,N′-tetraacetic acid; hampene; versene;N,N′-1,2-ethane diylbis-(N-(carboxymethyl)glycine); ethylenediaminetetra-acetic acid; N,N-bis(carboxymethyl)glycine; triglycollamic acid;trilone A; alpha,alpha′,alpha″-trimethylaminetricarboxylic acid;tri(carboxymethyl)amine; aminotriacetic acid; hampshire NTA acid;nitrilo-2,2′,2″-triacetic acid; titriplex i; nitrilotriacetic acid; andmixtures thereof.

The amount of water softening agent needed depends on the hardness ofthe water utilized in terms of Ca⁺⁺ and other multivalent ions.

The fiber mix slurry is heated to produce a heated fiber mix slurry. Thetemperature is that which is sufficient to remove a portion of thesulfopolyester from the multicomponent fiber. In one embodiment of theinvention, the fiber mix slurry is heated to a temperature ranging fromabout 50° C. to about 100° C. Other temperature ranges are from about70° C. to about 100° C., about 80° C. to about 100° C., and about 90° C.to about 100° C.

Optionally, the fiber mix slurry is mixed in a shearing zone. The amountof mixing is that which is sufficient to disperse and remove a portionof the water dispersible sulfopolyester from the multicomponent fiberand separate the water non-dispersible polymer microfibers. In oneembodiment of the invention, 90% of the sulfopolyester is removed. Inanother embodiment, 95% of the sulfopolyester is removed, and in yetanother embodiment, 98% or greater of the sulfopolyester is removed. Theshearing zone can comprise any type of equipment that can provideshearing action necessary to disperse and remove a portion of the waterdispersible sulfopolyester from the multicomponent fiber and separatethe water non-dispersible polymer microfibers. Examples of suchequipment include, but is not limited to, pulpers and refiners.

The water dispersible sulfopolyester in the multicomponent fiber aftercontact with water and heating will disperse and separate from the waternon-dispersible polymer fiber to produce a slurry mixture comprising asulfopolyester dispersion and the water non-dispersible polymermicrofibers. The water non-dispersible polymer microfibers can then beseparated from the sulfopolyester dispersion by any means known in theart. For examples, the slurry mixture can be routed through separatingequipment, such as for example, screens and filters. Optionally, thewater non-dispersible polymer microfibers may be washed once or numeroustimes to remove more of the water-dispersible sulfopolyester.

The removal of the water-dispersible sulfopolyester can be determined byphysical observation of the slurry mixture. The water utilized to rinsethe water non-dispersible polymer microfibers is clear if thewater-dispersible sulfopolyester has been mostly removed. If thewater-dispersible sulfopolyester is still being removed, the waterutilized to rinse the water non-dispersible polymer microfibers can bemilky. Further, if water-dispersible sulfopolyester remains on the waternon-dispersible polymer microfibers, the microfibers can be somewhatsticky to the touch.

The water-dispersible sulfopolyester can be recovered from thesulfopolyester dispersion by any method known in the art.

In another embodiment of this invention, a water non-dispersible polymermicrofiber is provided comprising at least one water non-dispersiblepolymer wherein the water non-dispersible polymer microfiber has anequivalent diameter of less than 5 microns and length of less than 25millimeters. This water non-dispersible polymer microfiber is producedby the processes previously described to produce microfibers. In anotheraspect of the invention, the water non-dispersible polymer microfiberhas an equivalent diameter of less than 3 microns and length of lessthan 25 millimeters. In other embodiments of the invention, the waternon-dispersible polymer microfiber has an equivalent diameter of lessthan 5 microns or less than 3 microns. In other embodiments of theinvention, the water non-dispersible polymer microfiber can have lengthsof less than 12 millimeters; less than 10 millimeters, less than 6.5millimeters, and less than 3.5 millimeters. The domains or segments inthe multicomponent fiber once separated yield the water non-dispersiblepolymer microfibers.

The instant invention also includes a fibrous article comprising thewater-dispersible fiber, the multicomponent fiber, microdenier fibers,or water non-dispersible polymer microfibers described hereinabove. Theterm “fibrous article” is understood to mean any article having orresembling fibers. Non-limiting examples of fibrous articles includemultifilament fibers, yarns, cords, tapes, fabrics, wet-laid webs,dry-laid webs, melt blown webs, spunbonded webs, thermobonded webs,hydroentangled webs, nonwoven webs and fabrics, and combinationsthereof; items having one or more layers of fibers, such as, forexample, multilayer nonwovens, laminates, and composites from suchfibers, gauzes, bandages, diapers, training pants, tampons, surgicalgowns and masks, feminine napkins; and the like. In addition, the waternon-dispersible microdfibers can be utilized in filter media for airfiltration, liquid filtration, filtration for food preparation,filtration for medical applications, and for paper making processes andpaper products. Further, the fibrous articles may include replacementinserts for various personal hygiene and cleaning products. The fibrousarticle of the present invention may be bonded, laminated, attached to,or used in conjunction with other materials which may or may not bewater-dispersible. The fibrous article, for example, a nonwoven fabriclayer, may be bonded to a flexible plastic film or backing of a waternon-dispersible material, such as polyethylene. Such an assembly, forexample, could be used as one component of a disposable diaper. Inaddition, the fibrous article may result from overblowing fibers ontoanother substrate to form highly assorted combinations of engineeredmelt blown, spunbond, film, or membrane structures.

The fibrous articles of the instant invention include nonwoven fabricsand webs. A nonwoven fabric is defined as a fabric made directly fromfibrous webs without weaving or knitting operations. The TextileInstitute defines nonwovens as textile structures made directly fromfiber rather than yarn. These fabrics are normally made from continuousfilaments or from fibre webs or batts strengthened by bonding usingvarious techniques, which include, but are not limited to, adhesivebonding, mechanical interlocking by needling or fluid jet entanglement,thermal bonding, and stitch bonding. For example, the multicomponentfiber of the present invention may be formed into a fabric by any knownfabric forming process. The resulting fabric or web may be convertedinto a microdenier fiber web by exerting sufficient force to cause themulticomponent fibers to split or by contacting the web with water toremove the sulfopolyester leaving the remaining microdenier fibersbehind.

In another embodiment of the invention, a process is provided forproducing a microdenier fiber web, comprising:

(A) spinning a water dispersible sulfopolyester having a glasstransition temperature (Tg) of at least 57° C. and one or more waternon-dispersible polymers immiscible with the sulfopolyester intomulticomponent fibers, the sulfopolyester comprising:

-   -   (i) about 50 to about 96 mole % of one or more residues of        isophthalic acid or terephthalic acid, based on the total acid        residues;    -   (ii) about 4 to about 30 mole %, based on the total acid        residues, of a residue of sodiosulfoisophthalic acid;    -   (iii) one or more diol residues wherein at least 25 mole %,        based on the total diol residues, is a poly(ethylene glycol)        having a structure

H—(OCH₂—CH₂)_(n)—OH

-   -   wherein n is an integer in the range of 2 to about 500; and    -   (iv) 0 to about 20 mole %, based on the total repeating units,        of residues of a branching monomer having 3 or more functional        groups wherein the functional groups are hydroxyl, carboxyl, or        a combination thereof.

wherein the multicomponent fibers have a plurality of segmentscomprising the water non-dispersible polymers wherein the segments aresubstantially isolated from each other by the sulfopolyester interveningbetween the segments;

(B) overlapping and collecting the multicomponent fibers of Step A toform a nonwoven web; and

(C) contacting the nonwoven web with water to remove the sulfopolyesterthereby forming a microdenier fiber web.

In another embodiment of the invention, the multicomponent fiberutilized contains less than 10 weight % of a pigment or filler, based onthe total weight of the fiber.

In another embodiment of the invention, a process for a microdenierfiber web is provided which comprises:

(A) spinning at least one water dispersible sulfopolyester and one ormore water non-dispersible polymers immiscible with the sulfopolyesterinto multicomponent fibers, the multicomponent fibers have a pluralityof domains comprising the water non-dispersible polymers wherein thedomains are substantially isolated from each other by the sulfopolyesterintervening between the domains; wherein the water dispersiblesulfopolyester exhibits a melt viscosity of less than about 12,000 poisemeasured at 240° C. at a strain rate of 1 rad/sec, and wherein thesulfopolyester comprising less than about 25 mole % of residues of atleast one sulfomonomer, based on the total moles of diacid or diolresidues;

(B) collecting the multicomponent fibers of Step A) to form a non-wovenweb; and

(C) contacting the non-woven web with water to remove the sulfopolyesterthereby forming a microdenier fiber web. In another embodiment, themulticomponent fiber utilized has an as-spun denier of less than about 6denier per filament.

In another embodiment of the invention, a process for a microdenierfiber web is provided which comprises:

(A) extruding at least one water dispersible sulfopolyester and one ormore water non-dispersible polymers immiscible with the waterdispersible sulfopolyester into multicomponent extrudates, themulticomponent extrudates have a plurality of domains comprising thewater non-dispersible polymers wherein the domains are substantiallyisolated from each other by the water dispersible sulfopolyesterintervening between the domains;

(B) melt drawing the multicomponent extrudates at a speed of at leastabout 2000 m/min to produce multicomponent fibers;

(C) collecting the multicomponent fibers of Step (B) to form a non-wovenweb; and

(D) contacting the non-woven web with water to remove the sulfopolyesterthereby forming a microdenier fiber web.

Prior to Step (C), the process can further comprise the step ofhydroentangling the multicomponent fibers of the non-woven web. In oneembodiment of the invention, the hydroentangling step results in a lossof less than about 20 weight % of the sulfopolyester contained in themulticomponent fibers, or less than 15 weight %, or less than 10 weight%. In furtherance of the goal of reducing the loss of sulfopolyesterduring hydroentanglement, the water used during this process can have atemperature of less than about 45° C., less than about 35° C., or lessthan about 30° C. In one embodiment of the invention, to minimize lossof sulfopolyester from the multicomponent fibers, the water used duringhydroentanglement is as close to room temperature as possible.Conversely, removal of the sulfopolyester polymer during Step (D) can becarried out using water having a temperature of at least about 45° C.,at least about 60° C., or at least about 80° C.

After hydroentanglement and prior to Step (D), the non-woven web mayunder go a heat setting step comprising heating the non-woven web to atemperature of at least about 100° C. or at least about 120° C. The heatsetting step relaxes out internal fiber stresses and aids in producing adimensionally stable fabric product. In other embodiments of theinvention, when the heat set material is reheated to the temperature towhich it was heated during the heat setting step that it exhibitssurface area shrinkage of less than about 5% of its original surfacearea, less than about 2% of the original surface area, or less thanabout 1% of its original surface area.

The sulfopolyester used in the multicomponent fiber can be any of thosedescribed herein. In one embodiment, the sulfopolyester has a meltviscosity of less than about 6000 poise measured at 240° C. at a strainrate of 1 rad/sec and comprises less than about 12 mole %, based on thetotal repeating units, of residues of at least one sulfomonomer. Thesetypes of sulfopolyesters are previously described herein.

Furthermore, the inventive method can comprise the step of drawing themulticomponent fiber at a fiber velocity of at least 2000 m/min, atleast about 3000 m/min, at least about 4000 m/min, or at least about5000 m/min.

In another embodiment of this invention, nonwoven articles comprisingwater non-dispersible polymer microfibers can be produced. The nonwovenarticle comprises water non-dispersible polymer microfibers and isproduced by a process selected from the group consisting of a dry-laidprocess and a wet-laid process. Multicomponent fibers and processes forproducing water non-dispersible polymer microfibers were previouslydisclosed in the specification.

In one embodiment of the invention, at least 1% of the waternon-dispersible polymer microfiber is contained in the nonwoven article.Other amounts of water non-dispersible polymer microfiber contained inthe nonwoven article are at least 10%, at least 25%, and at least 50%.

In another aspect of the invention, the nonwoven article can furthercomprise at least one other fiber. The other fiber can be any that isknown in the art depending on the type of nonwoven article to beproduced. In one embodiment of the invention, the other fiber can beselected from the group consisting cellulosic fiber pulp, glass fiber,polyester fibers, nylon fibers, polyolefin fibers, rayon fiberscellulose ester fibers, and mixtures thereof.

The nonwoven article can also further comprise at least one additive.Additives include, but are not limited to, starches, fillers, andbinders. Other additives are discussed in other sections of thisdisclosure.

Generally, manufacturing processes to produce these nonwoven articlesfrom water non-dispersible microfibers produced from multicomponentfibers can be split into the following groups: dry-laid webs, wet-laidwebs, and combinations of these processes with each other or othernonwoven processes.

Generally, dry-laid nonwoven articles are made with staple fiberprocessing machinery which is designed to manipulate fibers in the drystate. These include mechanical processes, such as, carding,aerodynamic, and other air-laid routes. Also included in this categoryare nonwoven articles made from filaments in the form of tow, andfabrics composed of staple fibers and stitching filaments or yards i.e.stitchbonded nonwovens. Carding is the process of disentangling,cleaning, and intermixing fibers to make a web for further processinginto a nonwoven article. The process predominantly aligns the fiberswhich are held together as a web by mechanical entanglement andfiber-fiber friction. Cards are generally configured with one or moremain cylinders, roller or stationary tops, one or more doffers, orvarious combinations of these principal components. One example of acard is a roller card. The carding action is the combing or working ofthe cut multicomponent fibers or the water non-dispersible polymermicrofibers between the points of the card on a series of interworkingcard rollers. Other types of cards include woolen, cotton, and randomcards. Garnetts can also be used to align these fibers.

The cut multicomponent fibers or water non-dispersible polymermicrofibers in the dried-laid process can also be aligned by air-laying.These fibers are directed by air current onto a collector which can be aflat conveyor or a drum.

Extrusion-formed webs can also be produced from the multicomponentsfibers of this invention. Examples include spunbonded and melt-blown.Extrusion technology is used to produce spunbond, meltblown, andporous-film nonwoven articles. These nonwoven articles are made withmachinery associated with polymer extrusion methods such as meltspinning, film casting, and extrusion coating. The nonwoven article isthen contacted with water to remove the water dispersible sulfopolyesterthus producing a nonwoven article comprising water non-dispersiblepolymer microfibers.

In the spunbond process, the water dispersible sulfopolyester and waternon-dispersible polymer are transformed directly to fabric by extrudingmulticomponent filaments, orienting them as bundles or groupings,layering them on a conveying screen, and interlocking them. Theinterlocking can be conducted by thermal fusion, mechanicalentanglement, hydroentangling, chemical binders, or combinations ofthese processes.

Meltblown fabrics are also made directly from the water dispersiblesulfopolyester and the water non-dispersible polymer. The polymers aremelted and extruded. When the melt passes through the extrusion orifice,it is blown with air at high temperature. The air stream attenuates andsolidifies the molten polymers. The multicomponent fibers can then beseparated from the air stream as a web and compressed between heatedrolls.

Combined spunbond and meltbond processes can also be utilized to producenonwoven articles.

Wet laid processes involve the use of papermaking technology to producenonwoven articles. These nonwoven articles are made with machineryassociated with pulp fiberizing, such as hammer mills, and paperforming.For example, slurry pumping onto continuous screens which are designedto manipulate short fibers in a fluid.

In one embodiment of the wet laid process, water non-dispersible polymermicrofibers are suspended in water, brought to a forming unit where thewater is drained off through a forming screen, and the fibers aredeposited on the screen wire.

In another embodiment of the wet laid process, water non-dispersiblepolymer microfibers are dewatered on a sieve or a wire mesh whichrevolves at the beginning of hydraulic formers over dewatering modules(suction boxes, foils and curatures) at high speeds of up to 1500 metersper minute. The sheet is then set on this wire mesh or sieve anddewatering proceeds to a solid content of approximately 20-30 weight %.The sheet can then be pressed and dried.

In another embodiment of the wet-laid process, a process is providedcomprising:

(A) optionally, rinsing the water non-dispersible polymer microfiberswith water;

(B) adding water to the water non-dispersible polymer microfibers toproduce a water non-dispersible polymer microfiber slurry;

(C) optionally, adding other fibers and/or additives to the waternon-dispersible polymer microfibers or slurry; and

(D) transferring the water non-dispersible polymer microfiberscontaining slurry to a wet-laid nonwoven zone to produce the nonwovenarticle.

In Step a), the number of rinses depends on the particular use chosenfor the water non-dispersible polymer microfibers. In Step b),sufficient water is added to the microfibers to allow them to be routedto the wet-laid nonwoven zone.

The wet-laid nonwoven zone comprises any equipment known in the art toproduce wet-laid nonwoven articles. In one embodiment of the invention,the wet-laid nonwoven zone comprises at least one screen, mesh, or sievein order to remove the water from the water non-dispersible polymermicrofiber slurry.

In another embodiment of the wet laid process, a process is providedcomprising:

(A) contacting a cut multicomponent fiber with water to remove a portionof the water dispersible sulfopolyester to produce a waternon-dispersible polymer microfiber slurry; wherein the waternon-dispersible polymer microfiber slurry comprises waternon-dispersible polymer microfibers and water dispersiblesulfopolyester;

(B) optionally, rinsing the water non-dispersible polymer microfiberswith water;

(C) optionally, adding other fibers and/or additives to the waternon-dispersible polymer slurry; and

(D) transferring the water non-dispersible polymer microfiberscontaining slurry to a wet-laid nonwoven zone to produce the nonwovenarticle.

In another embodiment of the invention, the water non-dispersiblepolymer microfiber slurry is mixed prior to transferring to the wet-laidnonwoven zone.

Web-bonding processes can also be utilized to produce nonwoven articles.These can be split into chemical and physical processes. Chemicalbonding refers to the use of water-based and solvent-based polymers tobind together the fibers and/or fibrous webs. These binders can beapplied by saturation, impregnation, spraying, printing, or applicationas a foam. Physical bonding processes include thermal processes such ascalendaring and hot air bonding, and mechanical processes such asneedling and hydroentangling. Needling or needle-punching processesmechanically interlock the fibers by physically moving some of thefibers from a near-horizontal to a near-vertical position.Needle-punching can be conducted by a needleloom. A needleloom generallycontains a web-feeding mechanism, a needle beam which comprises aneedleboard which holds the needles, a stripper plate, a bed plate, anda fabric take-up mechanism.

Stitchbonding is a mechanical bonding method that uses knittingelements, with or without yarn, to interlock the fiber webs. Examples ofstitchbonding machines include, but are not limited to, Maliwatt,Arachne, Malivlies, and Arabeva.

The nonwoven article can be held together by 1) mechanical fibercohesion and interlocking in a web or mat; 2) various techniques offusing of fibers, including the use of binder fibers, utilizing thethermoplastic properties of certain polymers and polymer blends; 3) useof a binding resin such as starch, casein, a cellulose derivative, or asynthetic resin, such as an acrylic latex or urethane; 4) powderadhesive binders; or 5) combinations thereof. The fibers are oftendeposited in a random manner, although orientation in one direction ispossible, followed by bonding using one of the methods described above.

The fibrous articles of our invention also may comprise one or morelayers of water-dispersible fibers, multicomponent fibers, ormicrodenier fibers. The fiber layers may be one or more nonwoven fabriclayers, a layer of loosely bound overlapping fibers, or a combinationthereof. In addition, the fibrous articles may include personal andhealth care products such as, but not limited to, child care products,such as infant diapers; child training pants; adult care products, suchas adult diapers and adult incontinence pads; feminine care products,such as feminine napkins, panty liners, and tampons; wipes;fiber-containing cleaning products; medical and surgical care products,such as medical wipes, tissues, gauzes, examination bed coverings,surgical masks, gowns, bandages, and wound dressings; fabrics;elastomeric yarns, wipes, tapes, other protective barriers, andpackaging material. The fibrous articles may be used to absorb liquidsor may be pre-moistened with various liquid compositions and used todeliver these compositions to a surface. Non-limiting examples of liquidcompositions include detergents; wetting agents; cleaning agents; skincare products, such as cosmetics, ointments, medications, emollients,and fragrances. The fibrous articles also may include various powdersand particulates to improve absorbency or as delivery vehicles. Examplesof powders and particulates include, but are not limited to, talc,starches, various water absorbent, water-dispersible, or water swellablepolymers, such as super absorbent polymers, sulfopolyesters, andpoly(vinylalcohols), silica, pigments, and microcapsules. Additives mayalso be present, but are not required, as needed for specificapplications. Examples of additives include, but are not limited to,oxidative stabilizers, UV absorbers, colorants, pigments, opacifiers(delustrants), optical brighteners, fillers, nucleating agents,plasticizers, viscosity modifiers, surface modifiers, antimicrobials,disinfectants, cold flow inhibitors, branching agents, and catalysts.

In addition to being water-dispersible, the fibrous articles describedabove may be flushable. The term “flushable” as used herein meanscapable of being flushed in a conventional toilet, and being introducedinto a municipal sewage or residential septic system, without causing anobstruction or blockage in the toilet or sewage system.

The fibrous article may further comprise a water-dispersible filmcomprising a second water-dispersible polymer. The secondwater-dispersible polymer may be the same as or different from thepreviously described water-dispersible polymers used in the fibers andfibrous articles of the present invention. In one embodiment, forexample, the second water-dispersible polymer may be an additionalsulfopolyester which, in turn, comprises:

(A) about 50 to about 96 mole % of one or more residues of isophthalicacid or terephthalic acid, based on the total acid residues;

(B) about 4 to about 30 mole %, based on the total acid residues, of aresidue of sodiosulfoisophthalic acid;

(C) one or more diol residues wherein at least 15 mole %, based on thetotal diol residues, is a poly(ethylene glycol) having a structure

H—(OCH₂—CH₂)_(n)—OH

wherein n is an integer in the range of 2 to about 500;

(D) 0 to about 20 mole %, based on the total repeating units, ofresidues of a branching monomer having 3 or more functional groupswherein the functional groups are hydroxyl, carboxyl, or a combinationthereof. The additional sulfopolyester may be blended with one or moresupplemental polymers, as described hereinabove, to modify theproperties of the resulting fibrous article. The supplemental polymermay or may not be water-dispersible depending on the application. Thesupplemental polymer may be miscible or immiscible with the additionalsulfopolyester.

The additional sulfopolyester may contain other concentrations ofisophthalic acid residues, for example, about 60 to about 95 mole %, andabout 75 to about 95 mole %. Further examples of isophthalic acidresidue concentrations ranges are about 70 to about 85 mole %, about 85to about 95 mole % and about 90 to about 95 mole %. The additionalsulfopolyester also may comprise about 25 to about 95 mole % of theresidues of diethylene glycol. Further examples of diethylene glycolresidue concentration ranges include about 50 to about 95 mole %, about70 to about 95 mole %, and about 75 to about 95 mole %. The additionalsulfopolyester also may include the residues of ethylene glycol and/or1,4-cyclohexanedimethanol. Typical concentration ranges of CHDM residuesare about 10 to about 75 mole %, about 25 to about 65 mole %, and about40 to about 60 mole %. Typical concentration ranges of ethylene glycolresidues are about 10 to about 75 mole %, about 25 to about 65 mole %,and about 40 to about 60 mole %. In another embodiment, the additionalsulfopolyester comprises is about 75 to about 96 mole % of the residuesof isophthalic acid and about 25 to about 95 mole % of the residues ofdiethylene glycol.

According to the invention, the sulfopolyester film component of thefibrous article may be produced as a monolayer or multilayer film. Themonolayer film may be produced by conventional casting techniques. Themultilayered films may be produced by conventional lamination methods orthe like. The film may be of any convenient thickness, but totalthickness will normally be between about 2 and about 50 mil.

The film-containing fibrous articles may include one or more layers ofwater-dispersible fibers as described above. The fiber layers may be oneor more nonwoven fabric layers, a layer of loosely bound overlappingfibers, or a combination thereof. In addition, the film-containingfibrous articles may include personal and health care products asdescribed hereinabove.

As described previously, the fibrous articles also may include variouspowders and particulates to improve absorbency or as delivery vehicles.Thus, in one embodiment, our fibrous article comprises a powdercomprising a third water-dispersible polymer that may be the same as ordifferent from the water-dispersible polymer components describedpreviously herein. Other examples of powders and particulates include,but are not limited to, talc, starches, various water absorbent,water-dispersible, or water swellable polymers, such aspoly(acrylonitiles), sulfopolyesters, and poly(vinyl alcohols), silica,pigments, and microcapsules.

Our novel fiber and fibrous articles have many possible uses in additionto the applications described above. One novel application involves themelt blowing a film or nonwoven fabric onto flat, curved, or shapedsurfaces to provide a protective layer. One such layer might providesurface protection to durable equipment during shipping. At thedestination, before putting the equipment into service, the outer layersof sulfopolyester could be washed off.

A further embodiment of this general application concept could involvearticles of personal protection to provide temporary barrier layers forsome reusable or limited use garments or coverings. For the military,activated carbon and chemical absorbers could be sprayed onto theattenuating filament pattern just prior to the collector to allow themelt blown matrix to anchor these entities on the exposed surface. Thechemical absorbers can even be changed in the forward operations area asthe threat evolves by melt blowing on another layer.

A major advantage inherent to sulfopolyesters is the facile ability toremove or recover the polymer from aqueous dispersions via flocculationor precipitation by adding ionic moieties (i.e., salts). Other methods,such as pH adjustment, adding nonsolvents, freezing, and so forth mayalso be employed. Therefore, fibrous articles, such as outer wearprotective garments, after successful protective barrier use and even ifthe polymer is rendered as hazardous waste, can potentially be handledsafely at much lower volumes for disposal using accepted protocols, suchas incineration.

Undissolved or dried sulfopolyesters are known to form strong adhesivebonds to a wide array of substrates, including, but not limited to fluffpulp, cotton, acrylics, rayon, lyocell, PLA (polylactides), celluloseacetate, cellulose acetate propionate, poly(ethylene)terephthalate,poly(butylene)terephthalate, poly(trimethylene)terephthalate,poly(cyclohexylene)terephthalate, copolyesters, polyamides (nylons),stainless steel, aluminum, treated polyolefins, PAN(polyacrylonitriles), and polycarbonates. Thus, our nonwoven fabrics maybe used as laminating adhesives or binders that may be bonded by knowntechniques, such as thermal, radio frequency (RF), microwave, andultrasonic methods. Adaptation of sulfopolyesters to enable RFactivation is disclosed in a number of recent patents. Thus, our novelnonwoven fabrics may have dual or even multifunctionality in addition toadhesive properties. For example, a disposable baby diaper could beobtained where a nonwoven of the present invention serves as both anwater-responsive adhesive as well as a fluid managing component of thefinal assembly.

Our invention also provides a process for water-dispersible fiberscomprising:

(A) heating a water-dispersible polymer composition to a temperatureabove its flow point, wherein the polymer composition comprises:

-   -   (i) residues of one or more dicarboxylic acids;    -   (ii) about 4 to about 40 mole %, based on the total repeating        units, of residues of at least one sulfomonomer having 2        functional groups and one or more metal sulfonate groups        attached to an aromatic or cycloaliphatic ring wherein the        functional groups are hydroxyl, carboxyl, or a combination        thereof; and    -   (iii) one or more diol residues wherein at least 20 mole %,        based on the total diol residues, is a poly(ethylene glycol)        having a structure

H—(OCH₂—CH₂)_(n)—OH

wherein n is an integer in the range of 2 to about 500; (iv) 0 to about25 mole based on the total repeating units, of residues of a branchingmonomer having 3 or more functional groups wherein the functional groupsare hydroxyl, carboxyl, or a combination thereof; wherein the polymercomposition contains less than 10 weight % of a pigment or filler, basedon the total weight of the polymer composition; and (II) melt spinningfilaments. As described hereinabove, a water-dispersible polymer,optionally, may be blended with the sulfopolyester. In addition, a waternon-dispersible polymer, optionally, may be blended with thesulfopolyester to form a blend such that blend is an immiscible blend.The term “flow point”, as used herein, means the temperature at whichthe viscosity of the polymer composition permits extrusion or otherforms of processing through a spinneret or extrusion die.

The dicarboxylic acid residue may comprise from about 60 to about 100mole % of the acid residues depending on the type and concentration ofthe sulfomonomer. Other examples of concentration ranges of dicarboxylicacid residues are from about 60 mole % to about 95 mole % and about 70mole % to about 95 mole %. The preferred dicarboxylic acid residues areisophthalic, terephthalic, and 1,4-cyclohexanedicarboxylic acids or ifdiesters are used, dimethyl terephthalate, dimethyl isophthalate, anddimethyl-1,4-cyclohexane dicarboxylate with the residues of isophthalicand terephthalic acid being especially preferred.

The sulfomonomer may be a dicarboxylic acid or ester thereof containinga sulfonate group, a diol containing a sulfonate group, or a hydroxyacid containing a sulfonate group. Additional examples of concentrationranges for the sulfomonomer residues are about 4 to about 25 mole %,about 4 to about 20 mole %, about 4 to about 15 mole %, and about 4 toabout 10 mole %, based on the total repeating units. The cation of thesulfonate salt may be a metal ion such as Li⁺, Na⁺, K⁺, Mg⁺⁺, Ca⁺⁺,Ni⁺⁺, Fe⁺⁺, and the like. Alternatively, the cation of the sulfonatesalt may be non-metallic such as a nitrogenous base as describedpreviously. Examples of sulfomonomer residues which may be used in theprocess of the present invention are the metal sulfonate salt ofsulfophthalic acid, sulfoterephthalic acid, sulfoisophthalic acid, orcombinations thereof. Another example of sulfomonomer which may be usedis 5-sod iosulfoisophthalic acid or esters thereof. If the sulfomonomerresidue is from 5-sod iosulfoisophthalic acid, typical sulfomonomerconcentration ranges are about 4 to about 35 mole %, about 8 to about 30mole %, and about 10 to 25 mole %, based on the total acid residues.

The sulfopolyester of our includes one or more diol residues which mayinclude aliphatic, cycloaliphatic, and aralkyl glycols. Thecycloaliphatic diols, for example, 1,3- and 1,4-cyclohexanedimethanol,may be present as their pure cis or trans isomers or as a mixture of cisand trans isomers. Non-limiting examples of lower molecular weightpolyethylene glycols, e.g., wherein n is from 2 to 6, are diethyleneglycol, triethylene glycol, and tetraethylene glycol. Of these lowermolecular weight glycols, diethylene and triethylene glycol are mostpreferred. The sulfopolyester may optionally include a branchingmonomer. Examples of branching monomers are as described hereinabove.Further examples of branching monomer concentration ranges are from 0 toabout 20 mole % and from 0 to about 10 mole %. The sulfopolyester of ournovel process has a Tg of at least 25° C. Further examples of glasstransition temperatures exhibited by the sulfopolyester are at least 30°C., at least 35° C., at least 40° C., at least 50° C., at least 60° C.,at least 65° C., at least 80° C., and at least 90° C. Although otherTg's are possible, typical glass transition temperatures of the drysulfopolyesters our invention are about 30° C., about 48° C., about 55°C., about 65° C., about 70° C., about 75° C., about 85° C., and about90° C.

The water-dispersible fibers can be prepared by a melt blowing process.The polymer is melted in an extruder and forced through a die. Theextrudate exiting the die is rapidly attenuated to ultrafine diametersby hot, high velocity air. The orientation, rate of cooling, glasstransition temperature (T_(g)), and rate of crystallization of the fiberare important because they affect the viscosity and processingproperties of the polymer during attenuation. The filament is collectedon a renewable surface, such as a moving belt, cylindrical drum,rotating mandrel, and so forth. Predrying of pellets (if needed),extruder zone temperature, melt temperature, screw design, throughputrate, air temperature, air flow (velocity), die air gap and set back,nose tip hole size, die temperature, die-to-collector (DCP) distance,quenching environment, collector speed, and post treatments are allfactors that influence product characteristics such as filamentdiameters, basis weight, web thickness, pore size, softness, andshrinkage. The high velocity air also may be used to move the filamentsin a somewhat random fashion that results in extensive interlacing. If amoving belt is passed under the die, a nonwoven fabric can be producedby a combination of over-lapping laydown, mechanical cohesiveness, andthermal bonding of the filaments. Overblowing onto another substrate,such as a spunbond or backing layer, is also possible. If the filamentsare taken up on an rotating mandrel, a cylindrical product is formed. Awater-dispersible fiber lay-down can also be prepared by the spunbondprocess.

The instant invention, therefore, further provides a process forwater-dispersible, nonwoven fabric comprising:

(A) heating a water-dispersible polymer composition to a temperatureabove its flow point, wherein the polymer composition comprises:

-   -   (i) residues of one or more dicarboxylic acids;    -   (ii) about 4 to about 40 mole %, based on the total repeating        units, of residues of at least one sulfomonomer having 2        functional groups and one or more metal sulfonate groups        attached to an aromatic or cycloaliphatic ring wherein the        functional groups are hydroxyl, carboxyl, or a combination        thereof;    -   (iii) one or more diol residues wherein at least 20 mole %,        based on the total diol residues, is a poly(ethylene glycol)        having a structure

H—(OCH₂—CH₂)_(n)—OH

-   -   wherein n is an integer in the range of 2 to about 500;    -   (iv) 0 to about 25 mole %, based on the total repeating units,        of residues of a branching monomer having 3 or more functional        groups wherein the functional groups are hydroxyl, carboxyl, or        a combination thereof; wherein the sulfopolyester has a glass        transition temperature (Tg) of at least 25° C.; wherein the        polymer composition contains less than 10 weight % of a pigment        or filler, based on the total weight of the polymer composition;

(B) melt-spinning filaments; and

(C) overlapping and collecting the filaments of Step (B) to form anonwoven fabric. As described hereinabove, a water-dispersible polymer,optionally, may be blended with the sulfopolyester. In addition, a waternon-dispersible polymer, optionally, may be blended with thesulfopolyester to form a blend such that blend is an immiscible blend.The dicarboxylic acid, sulfomonomer, and branching monomer residues areas described previously. The sulfopolyester has a Tg of at least 25° C.Further examples of glass transition temperatures exhibited by thesulfopolyester are at least 30° C., at least 35° C., at least 40° C., atleast 50° C., at least 60° C., at least 65° C., at least 80° C., and atleast 90° C. Although other Tg's are possible, typical glass transitiontemperatures of the dry sulfopolyesters our invention are about 30° C.,about 48° C., about 55° C., about 65° C., about 70° C., about 75° C.,about 85° C., and about 90° C.

In certain embodiments of the present invention, the water-wetmicrofibrous product (wet lap) produced after the multicomponent fibershave been cut, washed, and drained of excess water can be directly used(i.e., without further drying) in a wet-laid nonwoven process. Directuse of the wet lap product in a wet-laid nonwoven process avoids theneed for complete drying of the wet lap, thereby saving significantenergy and equipment costs. When the wet lap production facility islocated remotely from the facility for making wet-laid nonwovens, thewet lap can be packaged and transported from the wet lap productionlocation to the nonwoven production location. Such a wet lap compositionis described in further detail immediately below.

One embodiment of the present invention is directed to a wet lapcomposition comprising water and a plurality of synthetic fibers. Watercan make up at least 50, 55, or 60 weight % and/or not more than 90, 85,or 80 weight % of the wet lap composition. The synthetic fibers can makeup at least 10, 15, or 20 weight % and/or not more than 50, 45, or 40weight % of the wet lap composition. The water and the synthetic fibersin combination make up at least 95, 98, or 99 weight % of the wet lapcomposition. The synthetic fibers can have a length of at least 0.25,0.5, or 1 millimeter and/or not more than 25, 10, or 2 millimeters. Thesynthetic fibers can have a minimum transverse dimension at least 0.1,0.5, or 0.75 microns and/or not more than 10, 5, or 2 microns.

As used herein, “minimum transverse dimension” denotes the minimumdimension of a fiber measured perpendicular to the axis of elongation ofthe fiber by an external caliper method. As used herein, “maximumtransverse dimension” is the maximum dimension of a fiber measuredperpendicular to the axis of elongation of the fiber by the externalcaliper. FIGS. 1 a, 1 b, and 1 c depict how these dimensions may bemeasured in various fiber cross-sections. In FIGS. 1 a, 1 a, and 1 c,“TDmin” is the minimum transverse dimension and “TDmax” is the maximumtransverse dimension. As used herein, “external caliper method” denotesa method of measuring an outer dimension of a fiber where the measureddimension is the distance separating two coplanar parallel lines betweenwhich the fiber is located and where each of the parallel lines touchesthe external surface of the fiber on generally opposite sides of thefiber. All fiber dimensions provided herein (e.g., length, minimumtransverse dimension, and maximum transverse dimension) are the averagedimensions of the fibers belonging to the specified group.

The wet lap composition can further comprise a fiber finishingcomposition in an amount of at least 10, 50, or 100 ppmw and/or not morethan 1,000, 500, 250 ppmw. In one embobiment, the fiber finishingcomposition can comprise an oil, a wax, and/or a fatty acid. In anotherembodiment, the fiber finishing composition can comprise anaturally-derived fatty acid and/or a naturally-derived oil. In yetanother embodiment, the wherein the fiber finishing compositioncomprises mineral oil, stearate esters, sorbitan esters, and/orneatsfoot oil. In still another embodiment, the fiiber finishingcomposition comprises mineral oil.

The wet lap composition can further comprise a water dispersible polymerin an amount of at least 0.001, 0.01, or 0.1 and/or not more than 5, 2,or 1 weight %. In one embodiment the water dispersible polymer comprisesat least one sulfopolyester. Sulfopolyesters were previously describedin this disclosure.

The sulfopolyester can comprise:

-   -   (A) about 50 to about 96 percent, based on the total acid        residues, of residues of one or more dicarboxylic acids, wherein        the one or more dicarboxylic acids comprise terephthalic acid        and isophthalic acid,    -   (B) about 4 to about 40 mole %, based on the total acid        residues, of residues of at least one sulfomonomer having two        functional groups and one or more sulfonate groups attached to        an aromatic or cycloaliphatic ring wherein the functional groups        are hydroxyl, carboxyl, or a combination thereof, and    -   (C) one or more diol residues,

The sulfopolyester can have a glass transition temperature (Tg) of atleast 40° C. or at least 50° C., an inherent viscosity of at least 0.2dL/g measured in a 60/40 parts by weight solution ofphenol/tetrachloroethane solvent at 40° C. and at a concentration of 0.5grams of sulfopolyester in 100 mL of solvent, and a melt viscosity ofless than about 12,000, 8,000, or 6,000 poise measured at 240° C. at astrain rate of 1 rad/sec.

The water non-dispersible synthetic polymer of the wet lap compositioncan be selected from the group consisting of polyolefins, polyesters,copolyesters, polyamides, polylactides, polycaprolactones,polycarbonates, polyurethanes, cellulose esters, acrylics, polyvinylchlorides, and blends thereof. In one embodiment, the waternon-dispersible synthetic polymer is selected from the group consistingof polyethylene terephthalate homopolymer, polyethylene terephthalatecopolymers, polybutylene terephthalate, polypropylene terephthalate,nylon 6, nylon 66, and blends thereof.

The wet-lap composition can be made by a process comprising thefollowing steps:

(A) producing multicomponent fibers comprising at least one waterdispersible sulfopolyester and one or more water non-dispersiblesynthetic polymers immiscible with the water dispersible sulfopolyester,wherein the multicomponent fibers have an as-spun denier of less than 15dpf;

(B) cutting the multicomponent fibers into cut multicomponent fibershaving a length of less than 25 millimeters;

(C) contacting the cut multicomponent fibers with wash water to removethe water dispersible sulfopolyester thereby forming a slurry ofsynthetic fibers in a sulfopolyester dispersion, wherein thesulfopolyester dispersion comprises water and at least a portion of thesulfopolyester; and

(D) removing at least a portion of the sulfopolyester dispersion fromthe slurry to thereby producing a wet lap composition.

As discussed above, the wet lap composition can be used directly in awet-laid process to make a nonwoven articles. In order to use the wetlap in a wet-laid process, the wet lap composition is transferred fromits place of production to a wet-laid nonwoven zone. The wet lapcomposition can be combined with additional fibers in the wet-laidnonwoven zone and/or immediately upstream of the wet-laid nonwoven zone.The additional fibers can be selected from a group consisting ofcellulosic fiber pulp, inorganic fibers, polyester fibers, nylon fibers,lyocell fibers, polyolefin fibers, rayon fibers, cellulose ester fibers,and combinations thereof.

As part of the wet-laid process, the wet lap composition can be combinedwith dilution water in the wet-laid nonwoven zone and/or immediatelyupstream of the wet-laid nonwoven zone. The dilution water and wet lapcan be combined in amounts such that at least 50, 75, 90, or 95 parts byweight of the dilution water is used per one part of the wetlap.

In other embodiments of the invention, as shown in FIGS. 2, 3 a, 3 b,and 4, processes for producing a microfiber product stream are provided.Multicomponent fibers were previously discussed in this disclosure.Further disclosures concerning multicomponent fibers are provided in thefollowing patents and patents applications: U.S. Pat. Nos. 6,989,193;7,635,745; 7,902,094; 7,892,993; 7,687,143; and U.S. patent applicationSer. Nos. 12/199,304; 12/909,574; 13/273,692; 13/273,648; 13/273,710;13/273,720; 13/273,929, 13/273,937; 13/273,727, 13/273,737; 13/273,745;13/273,749; 12/966,502; 12/966,507; 12/975,450; 12/975,452; 12/975,456;13/053,615; 13/352,362; 13/433,812; 13/433,854; 61/471,259; 61/472,964;and 61/558,744, which are all hereby incorporated by reference to theextent they do not contradict the statements herein.

The terms “wet lap” and “microfiber product stream” will be usedinterchangeably in this disclosure.

In one embodiment of the invention as shown in FIG. 2, a process forproducing a microfiber product stream is provided. The processcomprises:

(A) contacting short cut multicomponent fibers 101 having a length ofless than 25 millimeters with a heated aqueous stream 801 in a fiberopening zone 400 to remove a portion of the water dispersiblesulfopolyester to produce an opened microfiber slurry 401; wherein theshort cut multicomponent fibers comprise at least one water dispersiblesulfopolyester and at least one water non-dispersible synthetic polymerimmiscible with the water dispersible sulfopolyester; wherein the heatedaqueous stream 801 is at a temperature of at least 40° C.; wherein theopened microfiber slurry 401 comprises water, microfiber, and waterdispersible sulfopolyester; and

(B) routing the opened microfiber slurry 401 to a primary solid liquidseparation zone 500 to produce the microfiber product stream 503 and afirst mother liquor stream 501; wherein the first mother liquor stream501 comprises water and the water dispersible sulfopolyester.

In this embodiment of the invention, the fiber slurry zone 200, mix zone300, and the fiber opening zone 400 as shown in FIG. 4 have beencombined into one unit operation in the opening process zone 1100. Theopening process zone 1100 comprises a fiber opening zone 400.

A treated aqueous stream 103 for use in the process can be produced byrouting an aqueous stream 102 to an aqueous treatment zone 1000 toproduce a treated aqueous stream 103. The aqueous stream compriseswater. In embodiments of the invention, the concentration of monovalentmetal cations in the treated aqueous stream 103 can be less than about1000 ppm by weight, less than about 500 ppm by weight, less than about100 ppm by weight, or less than about 50 ppm by weight. Removal ofdivalent and multivalent metal cations from the aqueous stream 102 isone function of the aqueous treatment zone 1000. In other embodiments ofthe invention, the concentration of divalent and multivalent cations isless than about 50 ppm by weight, less than about 25 ppm by weight, lessthan about 10 ppm by weight, or less than about 5 ppm by weight. Thetemperature of stream 103 can range from ground water temperature toabout 40° C.

The treatment of the aqueous stream 102 in the aqueous treatment zone1000 can be accomplished in any way know in the art. In one embodiment,aqueous treatment zone 1000 comprises distillation equipment whereinwater vapor is generated and condensed to produce the treated aqueousstream 103. In another embodiment, water is routed to a reverse osmosismembrane separation capable of separating monovalent and divalent metalcations from water to produce the treated aqueous stream 103. In anotherembodiment, water is routed to an ion exchange resin to generate thetreated aqueous stream 103 with acceptably low concentration of metalcations. In yet another embodiment, water can be routed to a commercialwater softening apparatus to generate the treated aqueous stream 103with an acceptably low concentration of divalent and multivalent metalcations. It is understood that any combinations of these water treatmentoptions may be employed to achieve the required treated watercharacteristics.

The treated aqueous stream 103 may be routed to any location in theprocess where it is needed. In one embodiment, a portion of stream 103is routed to a primary solid liquid separation zone 500 to serve as acloth wash and/or a wash for solids contained in the primary solidliquid separation zone 500.

In one embodiment, at least a portion of the treated aqueous stream 103is routed to heat exchanger zone 800 to produce a heated aqueous stream.One function of heat exchanger zone 800 is to generate a heated aqueousstream 801 at a specific and controlled temperature.

In one embodiment, streams that can feed heat exchanger zone 800 are thetreated aqueous stream 103 and the second mother liquor stream 601. Inanother embodiment, streams that can feed heat exchanger zone 800comprise the treated aqueous stream 103, a portion of the primaryrecovered water stream 703, a portion of the first mother liquor stream501, and a portion the second mother liquor stream 601.

Any equipment know in the art for controlling the temperature of stream801 may be used including, but not limited to, any heat exchanger withsteam used to provide a portion of the required energy, any heatexchanger with a heat transfer fluid used to provide a portion of therequired energy, any heat exchanger with electrical heating elementsused to provide a portion of the required energy, and any vessel or tankwith direct steam injection wherein the steam condenses and thecondensate mixes with the water feeds to heat exchanger zone 800. Themulticomponent fiber stream 90 is routed to fiber cutting zone 100 togenerate cut multicomponent fiber stream 101. The multicomponent fibercan be of any multicomponent structure known in the art. Themulticomponent fiber comprises a water dispersible sulfopolyester and awater non-dispersible polymer as previously discussed in thisdisclosure.

Any equipment know in the art may be used to cut multicomponent fiberstream 90 to generate cut multicomponent fiber stream 101. In oneembodiment, the length of the cut fibers in the cut multicomponent fiberstream 101 is less than about 50 mm. In other embodiments, the length ofcut fibers in the cut multicomponent fiber stream 101 is less than about25 mm, less than about 20 mm, less than about 15 mm, less than about 10mm, less than about 5 mm, or less than 2.5 mm.

The cut multicomponent fiber stream 101 and a portion of the heatedtreated aqueous stream 801 are routed to a fiber opening zone 400 togenerate opened microfiber slurry 401. One function of fiber openingzone 400 is to separate the water dispersible polymer from the cutmulticomponent fiber such that at least a portion of the waternon-dispersible polymer microfibers separate from the cut multicomponentfiber and become suspended in the opened microfiber slurry 401. Inanother embodiment of the invention, from about 50 weight % to about 100weight % of water non-dispersible polymer microfiber contained in thecut multicomponent fiber slurry 201 becomes suspended in the openedmicrofiber slurry 401 as water non-dispersible polymer microfibers andis no longer a part of the cut multicomponent fiber. In otherembodiments, from about 75 weight % to about 100 weight %, from about 90weight % to about 100 weight %, or from about 95 weight % to about 100weight % of the water non-dispersible polymer microfiber contained inthe cut multicomponent fiber stream 201 becomes suspended in the openedmicrofiber slurry 401 as water non-dispersible polymer microfibers andare no longer a part of a cut multicomponent fiber.

The diameter or denier of the starting cut multicomponent fiber instream 201 impacts the extent of separation of the water dispersiblesulfopolyester from the cut multicomponent fiber in the fiber openingzone 400. Typical multicomponent fiber types generally have a diameterin the range from about 12 microns to about 20 microns. Usefulmulticomponent fibers can have larger starting diameters to a size ofabout 40 microns diameter or more. The time required to separate adesired amount of water dispersible sulfopolyester from the cutmulticomponent fiber increases as the diameter of the cut multicomponentfiber in stream 201 increases.

In this embodiment of the invention, fiber slurry zone 200, mix zone300, and fiber opening zone 400 as shown in FIG. 4 are combined andaccomplished in a single unit operation as shown in FIG. 2. In thisembodiment, the cut multicomponent fiber stream 101 is routed directlyto single unit operation where it mixed with the heated aqueous stream801 within fiber opening zone 400. For example, a batch mixing devicewhere the opening or washing of the cut multicomponent fibers isaccomplished in a single batch mixing device wherein cut multicomponentfiber stream 101 and the heated aqueous stream 801 are added directly tothe in the fiber opening zone 400. The fiber opening zone can compriseat least one mix tank. In this embodiment, the combined functions ofzones 200, 300 and 400 may be accomplished in a continuous stirred tankreactor as shown in FIGS. 5 b and 5 c. In this embodiment, the combinedfunctions of zones 200, 300 and 400 may be accomplished in any batch orcontinuous mixing device capable of achieving the functionalrequirements of residence time, temperature, and mixing shear forcesrequired for proper function of zones 200, 300, and 400.

Residence time, temperature, and shear forces in the fiber opening zone400 also influence the extent of separation of the water dispersiblesulfopolyester from the cut multicomponent fiber. The conditionsinfluencing the opening process in fiber opening zone 400 compriseresidence time, slurry temperature, and shear forces where the ranges ofwater temperature, residence time in the fiber opening zone 400, andamount of applied shear are dictated by the need to separate the waterdispersible sulfopolyester from the starting multicomponent fiber to asufficient degree to result in water non-dispersible polymer microfibersbecoming separated and suspended in the continuous aqueous phase of theopened microfiber slurry 401.

Residence time, temperature, and shear forces in fiber opening zone 400influence the extent of separation of the water dispersiblesulfopolyester from the cut multicomponent fiber. The temperature of thefiber opening zone 400 can range from about 55 degrees centigrade toabout 100 degrees centigrade, from about 60 degrees centigrade to about90 degrees centigrade, or from about 65 degrees centigrade to about 80degrees centigrade. The residence time in the fiber opening zone 400 canrange from about 5 minutes to about 10 seconds, from about 3 minutes toabout 20 seconds, or from about 2 minutes to about 30 seconds.Sufficient mixing is maintained in fiber opening zone 400 to maintain asuspension of cut water non-dispersible polymer microfibers such thatthe settling of the cut microfibers is minimal. In other embodiments ofthe invention, the mass per unit time of cut water non-dispersiblemicrofibers settling in the fiber opening zone 400 is less than about 5%of the mass per unit time of cut water non-dispersible polymermicrofibers entering the zone 400, less than about 3% of the mass perunit time of cut water non-dispersible polymer microfibers entering zone400, or less than about 1% of the mass per unit time of cut waternon-dispersible polymer microfibers entering the fiber opening zone 400.

Fiber opening in fiber opening zone 400 may be accomplished in anyequipment capable of allowing for acceptable ranges of residence time,temperature, and mixing. Examples of suitable equipment include, but arenot limited to, an agitated batch tank, a continuous stirred tankreactor, as shown in FIGS. 6 b and 6 c, and a pipe with sufficient flowto minimize solids from settling out of the slurry as shown in FIG. 6 a.One example of a unit operation to accomplish fiber opening in fiberopening zone 400 is a plug flow reactor where the heated multicomponentfiber slurry 301 is routed to zone 400 plug flow device, typically acircular pipe or conduit. The residence time of material in a plug flowdevice is calculated by dividing the filled volume within the device bythe volumetric flow rate in the device. Velocity of the mass in thedevice is defined by the cross sectional area of the flow channeldivided by the volumetric flow of the liquid through the device.

In other embodiments of the invention, the fiber opening zone 400 cancomprise a pipe or conduit wherein the velocity of mass flowing in thepipe can range from 0.1 ft/second to about 20 feet/second, from 0.2ft/sec to about 10 ft/sec, or from about 0.5 ft/sec to about 5 ft/sec.For flow of a fluid or slurry in a pipe or conduit, the Reynolds numberRe is a dimensionless number useful for describing the turbulence ormotion of fluid eddy currents that are irregular with respect both todirection and time. For flow in a pipe or tube, the Reynolds number isgenerally defined as:

${Re} = {\frac{\rho \; {vD}_{H}}{\mu} = {\frac{{vD}_{H}}{\nu} = \frac{{QD}_{H}}{\; {\nu \; A}}}}$

Where:

-   -   D_(H) is the hydraulic diameter of the pipe; L, (m).    -   Q is the volumetric flow rate (m³/s).    -   A is the pipe cross-sectional area (m²).    -   v is the mean velocity of the object relative to the fluid (SI        units: m/s).    -   μ is the dynamic viscosity of the fluid (Pa·s or N·s/m² or        kg/(m·s)).    -   v is the kinematic viscosity (v=μ/ρ) (m²/s).    -   ρ is the density of the fluid (kg/m³).        For flow in a pipe of diameter D, experimental observations show        that for fully developed flow, laminar flow occurs when        Re_(D)<2000, and turbulent flow occurs when Re_(D)>4000. In the        interval between 2300 and 4000, laminar and turbulent flows are        possible (‘transition’ flows), depending on other factors, such        as, pipe roughness and flow uniformity.

Fiber opening zone 400 can comprise a pipe or conduit to facilitate theopening process, and the Reynolds number for flow through the pipe orconduit in fiber opening zone 400 can range from about 2,100 to about6,000, from about 3,000 to about 6,000, or from about 3,500 to about6,000. In other embodiments, the fiber opening zone 400 can comprise apipe or conduit to facilitate the opening process, and the Reynoldsnumber for flow through the pipe or conduit is at least 2,500, at leastabout 3,500, or at least about 4,000.

Fiber opening zone 400 can be achieved in a pipe or conduit containing amixing device inserted within the pipe or conduit. The device cancomprise an in-line mixing device. The in-line mixing device can be astatic mixer with no moving parts. In another embodiment, the in-linemixing device comprises moving parts. Without being limiting, such anelement is a mechanical device for the purpose of imparting more mixingenergy to the heated multicomponent fiber slurry 301 than achieved bythe flow through the pipe. The device can be inserted at the beginningof the pipe section used as the fiber opening zone, at the end of thepipe section, or at any location within the pipe flow path.

The opened fiber slurry stream 401 comprising water non-dispersiblepolymer microfiber, water, and water dispersible sulfopolyester can berouted to a primary solid liquid separation zone 500 to generate amicrofiber product stream 503 comprising microfiber and a first motherliquor stream 501. In one embodiment, the first mother liquor stream 501comprises water and water dispersible sulfopolyester.

The weight % of solids in the opened microfiber slurry 401 can rangefrom about 0.1 weight % to about 20 weight %, from about 0.3 weight % toabout 10 weight %, from about 0.3 weight % to about 5 weight %, or fromabout 0.3 weight % to about 2.5 weight %.

The weight % of solids in the microfiber product stream 503 can rangefrom about 10 weight % to about 65 weight %, from about 15 weight % toabout 50 weight %, from about 25 weight % to about 45 weight %, or fromabout 30 weight % to about 40 weight %.

Separation of the microfiber product stream 503 from the openedmicrofiber slurry 401 can be accomplished by any method known in theart. In one embodiment, wash stream 103 comprising water is routed tothe primary solid liquid separation zone 500. Wash stream 103 can beused to wash the microfiber product stream in the primary solid liquidseparation zone 500 and/or the filter cloth media in the primary solidliquid separation zone 500 to generate wash liquor stream 502. A portionup to 100 weight % of wash liquor stream 502 can be combined with theopened microfiber slurry 401 prior to entering the primary solid liquidseparation zone 500. A portion up to 100 weight % of wash liquor stream502 can be routed to a second solid liquid separation zone 600. Washliquor stream 502 can contain microfiber. In one embodiment, the gramsof microfiber mass breaking though the filter media with openings up to2000 microns in the primary solid liquid separation zone 500 ranges fromabout 1 to 2 grams/cm² of filter area. In other embodiments of theinvention, the filter openings in the filter media in the primary solidliquid separation zone 500 can range from about 43 microns to 3000microns, from about 100 microns to 2000 microns, or from about 500microns to about 2000 microns.

Separation of the microfiber product stream from the opened microfiberslurry in primary solid liquid separation zone 500 may be accomplishedby a single or multiple solid liquid separation devices. Separation inthe primary solid liquid separation zone 500 may be accomplished by asolid liquid separation device or devices operated in batch and orcontinuous fashion. Suitable solid liquid separation devices in theprimary solid liquid separation zone 500 can include, but is not limitedto, at least one of the following: perforated basket centrifuges,continuous vacuum belt filters, batch vacuum nutschfilters, batchperforated settling tanks, twin wire dewatering devices, continuoushorizontal belt filters with a compressive zone, non vibrating inclinedscreen devices with wedge wire filter media, continuous vacuum drumfilters, dewatering conveyor belts, and the like.

In one embodiment, the primary solid liquid separation zone 500comprises a twin wire dewatering device wherein the opened microfibersturry 401 is routed to a tapering gap between a pair of travelingfilter cloths traveling in the same direction. In the first zone of thetwin wire dewatering device, water drains from the opened microfiberslurry 401 due to gravity and the every narrowing gap between the twomoving filter cloths. In a downstream zone of the twin wire dewateringdevice, the two filter cloths and the microfiber mass between the twofilter cloths are compressed one or more times to mechanically reducemoisture in the microfiber mass. In one embodiment, mechanicaldewatering is accomplished by passing the two filter cloths andcontained microfiber mass through at least one set of rollers that exerta compressive force on the two filter cloths and microfiber massbetween. In another embodiment, mechanical dewatering is accomplished bypassing the two filter cloths and microfiber mass between at least oneset of pressure rollers.

In other embodiments of the invention, the force exerted by mechanicaldewatering for each set of pressure rollers can range from about 25 toabout 300 lbs/linear inch of filter media width, from about 50 to about200 lbs/linear inch of filter media width, or from about 70 to about 125lbs/linear inch of filter media width. The microfiber product stream 503is discharged from the twin wire water dewatering device as the twofilter cloths separate and diverge at the solids discharge zone of thedevice. The thickness of the discharged microfiber mass can range fromabout 0.2 inches to about 1.5 inches, from about 0.3 inches to about1.25 inches, or from about 0.4 inches to about 1 inch. In oneembodiment, a wash stream comprising water is continuously applied tothe filter media. In another embodiment, a wash stream comprising wateris periodically applied to the filter media.

In another embodiment, the primary solid liquid separation zone 500comprises a belt filter device comprising a gravity drainage zone and apressure dewatering zone as illustrated in FIG. 7. Opened microfiberslurry 401 is routed to a tapering gap between a pair of moving filtercloths traveling in the same direction which first pass through agravity drainage zone and then pass through a pressure dewatering zoneor press zone comprising a convoluted arrangement of rollers asillustrated in FIG. 6 b. As the belts are fed through the rollers, wateris squeezed out of the solids. When the belts pass through the finalpair of rollers in the process, the filter cloths are separated and thesolids exit the belt filter device.

In another embodiment of the invention, at least a portion of the watercontained in the first mother liquor stream 501 comprising water andwater dispersible sulfopolyester polymer is recovered and recycled. Thefirst mother liquor stream 501 can be recycled to the primary solidliquid separation zone 500. Depending on the efficiency of the primaryliquid separation zone in the removal of the water non-dispersiblemicrofiber, the first mother liquid stream 501 can be recycled to thefiber opening zone 400, or the heat exchanger zone 800 prior to beingrouted to Zone 400. The first mother liquor stream 501 can contain asmall amount of solids comprising water non-dispersible polymermicrofiber due to breakthrough and cloth wash. In one embodiment, thegrams of water non-dispersible polymer microfiber mass breaking thoughfilter media in the primary solid liquid separation zone with openingsup to 2000 microns ranges from about 1 to about 2 grams/cm² of filterarea. It is desirable to minimize the water non-dispersible polymermicrofiber solids in the first mother liquor stream 501 prior to routingstream 501 to the primary concentration zone 700 and heat exchange zone800 where water non-dispersible polymer microfiber solids can collectand accumulate in the zones having a negative impact on their function.

A secondary solid liquid separation zone 600 can serve to remove atleast a portion of water non-dispersible polymer microfiber solidspresent in the first mother liquor stream 501 to generate a secondarywet cake stream 602 comprising water non-dispersible microfiber and asecond mother liquor stream 601 comprising water and water dispersiblesulfopolyester.

In one embodiment, the second mother liquor stream 601 can be routed toa primary concentration zone 700 and or heat exchanger zone 800 whereinthe weight % of the second mother liquor stream 601 routed to theprimary concentration zone 700 can range from 0% to 100% with thebalance of the stream being routed to heat exchanger zone 800. Thesecond mother liquor stream 601 can be recycled to the fiber openingzone 400, or the heat exchanger zone 800 prior to being routed to Zone400. The amount of the water dispersible sulfopolyester in the secondmother liquor stream routed to the fiber opening zone 400 can range fromabout 0.01 weight % to about 7 weight %, based on the weight % of thesecond mother liquor stream, or from about 0.1 weight % to about 7weight %, from about 0.2 weight % to about 5 weight %, or from about 0.3weight % to about 3 weight %.

Any portion of the second mother liquor 601 routed to primaryconcentration zone is subjected to a separation process to generate aprimary recovered water stream 703 and a primary polymer concentratestream 702 enriched in water dispersible sulfopolyester wherein theweight % of water dispersible sulfopolyester in the primary polymerconcentrate stream 702 can range from about 5 weight % to about 85%,from about 10 weight % to about 65 weight %, or from about 15 weight %to about 45 weight %. The primary recovered water stream 703 can berecycled to the fiber opening zone 400, or the heat exchanger zone 800prior to being routed to Zone 400. The amount of the water dispersiblesulfopolyester in the second mother liquor stream routed to the fiberopening zone 400 can range from about 0.01 weight % to about 7 weight %,based on the weight % of the second mother liquor stream, or from about0.1 weight % to about 7 weight %, from about 0.2 weight % to about 5weight %, or from about 0.3 weight % to about 3 weight %.

Water can be removed from the second mother liquor stream 601 by anymethod know in the art in the primary concentration zone 700 to producethe primary polymer concentrate stream 702. In one embodiment, removalof water involves an evaporative process by boiling water away in batchor continuous evaporative equipment. For example, at least one thin filmevaporator can be used for this application. In another embodiment,membrane technology comprising nanofiltration media can be used togenerate the primary polymer concentrate stream 702. In anotherembodiment, a process comprising extraction equipment may be used toextract water dispersible polymer from the second mother liquor stream601 and generate the primary polymer concentrate stream 702. It isunderstood than any combination of evaporation, membrane, and extractionsteps may be used to separate the water dispersible sulfopolyester fromthe second mother liquor stream 601 and generate the primary polymerconcentrate stream 702. The primary polymer concentration stream 702 maythen exit the process.

In one embodiment, the primary polymer concentrate stream 702 can berouted to a secondary concentration zone 900 to generate a meltedpolymer stream 903 comprising water dispersible sulfopolyester whereinthe weight % of polymer ranges from about 95% to about 100% and a vaporstream 902 comprising water. In one embodiment, the 903 comprises waterdispersible sulfopolyester. Equipment suitable for the secondaryconcentration zone 900 includes any equipment known in the art capableof being fed an aqueous dispersion of water dispersible polymer andgenerating a 95% to 100% water dispersible polymer stream 903. Thisembodiment comprises feeding an aqueous dispersion of water dispersiblesulfopolyester polymer to a secondary concentration zone 902. Thetemperature of feed stream is typically below 100° C.

In one embodiment, the secondary concentration zone 900 comprises atleast one device characterized by a jacketed tubular shell containing arotating convey screw wherein the convey screw is heated with a heattransfer fluid or steam and comprises both convey and high shear mixingelements. The jacket or shell is vented to allow for vapor to escape.The shell jacket may be zoned to allow for different temperature setpoints along the length of the device. During continuous operation, theprimary polymer concentrate stream 702 comprises water and waterdispersible sulfopolyester and is continuously fed to the secondaryconcentration zone 900. Within the device, during steady state, massexists in at least three distinct and different forms. Mass first existsin the device as an aqueous dispersion of water dispersiblesulfopolyester polymer. As the aqueous dispersion of sulfopolyesterpolymer moves through the device, water is evaporated due to the heat ofthe jacket and internal screw. When sufficient water is evaporated, themass becomes a second form comprising a viscous plug at a temperatureless than the melt temperature of the sulfopolyester polymer. Theaqueous dispersion cannot flow past this viscous plug and is confined tothe first aqueous dispersion zone of the device. Due to the heat of thejacket, heat of the internally heated screw, and the heat due to mixingshear forces of this high viscosity plug mass, substantially all thewater present at this location evaporates, and the temperature risesuntil the melt temperature of the sulfopolyester is reached resulting inthe third and final physical form of mass in the device comprisingmelted sulfopolyester polymer. The melted sulfopolyester polymer thenexits the device through an extrusion dye and is typically cooled andcut into pellets by any fashion know in the art. It is understood thatthe device for secondary concentration zone 900 described above may alsobe operated in batch fashion wherein the three physical forms of massdescribed above occur throughout the length of the device but atdifferent times in sequential order beginning with the aqueousdispersion, the viscous plug mass, and finally the sulfopolyester melt.

In one embodiment, vapor generated in the secondary concentration zone900 may be condensed and routed to heat exchanger zone 800, discarded,and/or routed to wash stream 103. In another embodiment, condensed vaporstream 902 comprising water vapor can be routed to heat exchanger zone800 to provide at least part of the energy required for generating therequired temperature for stream 801. The melted polymer stream 903comprising water dispersible polymer comprising sulfopolyester in themelt phase can be cooled and chopped into pellets by any method known inthe art.

Impurities can enter the process and concentrated in water recovered andrecycled. One or more purge streams (603 and 701) can be utilized tocontrol the concentration of impurities in the second mother liquor 601and primary recovered water stream 701 to acceptable levels. In oneembodiment, a portion of the second mother liquor stream 601 can beisolated and purged from the process. In one embodiment, a portion ofthe primary recovered water stream 701 can be isolated and purged fromthe process.

In another embodiment of the invention, as shown in FIG. 3 a, a processfor producing a microfiber product stream is provided. The processcomprises:

(A) contacting short cut multicomponent fibers 101 having a length ofless than 25 millimeters with a treated aqueous stream 103 in a fiberslurry zone 200 to produce a short cut multicomponent fiber slurry 201;wherein the short cut multicomponent fibers 101 comprise at least onewater dispersible sulfopolyester and at least one water non-dispersiblesynthetic polymer immiscible with the water dispersible sulfopolyester;and wherein the treated aqueous stream 103 is at a temperature of lessthan 40° C.;(B) contacting the short cut multicomponent fiber slurry 201 and aheated aqueous stream 801 in a fiber opening zone 400 to remove aportion of the water dispersible sulfopolyester to produce an openedmicrofiber slurry 401; wherein the opened microfiber slurry compriseswater non-dispersible polymer microfiber, water dispersiblesulfopolyester, and water; and(C) routing the opened microfiber slurry 401 to a primary solid liquidseparation zone 500 to produce the microfiber product stream 503 and afirst mother liquor stream 501; wherein the first mother liquor stream501 comprises water and the water dispersible sulfopolyester.

In this embodiment of the invention, the mix zone 300 and the fiberopening zone 400 as shown in FIG. 4 have been combined into one unitoperation in the opening process zone 1100. The opening process zone1100 comprises a fiber slurry zone 200 and a fiber opening zone 400.

A treated aqueous stream 103 for use in the process can be produced byrouting an aqueous stream 102 to an aqueous treatment zone 1000 toproduce a treated aqueous stream 103. The aqueous stream compriseswater. In embodiments of the invention, the concentration of monovalentmetal cations in the treated aqueous stream 103 can be less than about1000 ppm by weight, less than about 500 ppm by weight, less than about100 ppm by weight, or less than about 50 ppm by weight. Removal ofdivalent and multivalent metal cations from the aqueous stream 102 isone function of the aqueous treatment zone 1000. In other embodiments ofthe invention, the concentration of divalent and multivalent cations isless than about 50 ppm by weight, less than about 25 ppm by weight, lessthan about 10 ppm by weight, or less than about 5 ppm by weight. Thetemperature of stream 103 can range from ground water temperature toabout 40° C.

The treatment of the aqueous stream 102 in the aqueous treatment zone1000 can be accomplished in any way know in the art. In one embodiment,aqueous treatment zone 1000 comprises distillation equipment whereinwater vapor is generated and condensed to produce the treated aqueousstream 103. In another embodiment, water is routed to a reverse osmosismembrane separation capable of separating monovalent and divalent metalcations from water to produce the treated aqueous stream 103. In anotherembodiment, water is routed to an ion exchange resin to generate thetreated aqueous stream 103 with acceptably low concentration of metalcations. In yet another embodiment, water can be routed to a commercialwater softening apparatus to generate the treated aqueous stream 103with an acceptably low concentration of divalent and multivalent metalcations. It is understood that any combinations of these water treatmentoptions may be employed to achieve the required treated watercharacteristics.

The treated aqueous stream 103 may be routed to any location in theprocess where it is needed. In one embodiment, a portion of stream 103is routed to a primary solid liquid separation zone 500 to serve as acloth wash and/or a wash for solids contained in the primary solidliquid separation zone 500.

In one embodiment, at least a portion of the treated aqueous stream 103is routed to heat exchanger zone 800. In another embodiment, at least aportion of treated aqueous stream 103 is routed to a fiber slurry zone200. In another embodiment, at least a portion of the treated aqueousstream 103 is routed to heat exchanger zone 800 and at least a portionof the treated aqueous stream 103 is routed to the fiber slurry zone200. One function of heat exchanger zone 800 is to generate a heatedaqueous stream 801 at a specific and controlled temperature.

In one embodiment, streams that can feed heat exchanger zone 800 are thetreated aqueous stream 103 and the second mother liquor stream 601. Inanother embodiment, streams that can feed heat exchanger zone 800comprise the treated aqueous stream 103, the primary recovered waterstream 703, the first mother liquor stream 501, and the second motherliquor stream 601.

Any equipment know in the art for controlling the temperature of stream801 may be used including, but not limited to, any heat exchanger withsteam used to provide a portion of the required energy, any heatexchanger with a heat transfer fluid used to provide a portion of therequired energy, any heat exchanger with electrical heating elementsused to provide a portion of the required energy, and any vessel or tankwith direct steam injection wherein the steam condenses and thecondensate mixes with the water feeds to heat exchanger zone 800. Themulticomponent fiber stream 90 is routed to fiber cutting zone 100 togenerate cut multicomponent fiber stream 101. The multicomponent fibercan be of any multicomponent structure known in the art. Themulticomponent fiber comprises a water dispersible sulfopolyester and awater non-dispersible polymer as previously discussed in thisdisclosure.

Any equipment know in the art may be used to cut multicomponent fiberstream 90 to generate cut multicomponent fiber stream 101. In oneembodiment, the length of the cut fibers in the cut multicomponent fiberstream 101 is less than about 50 mm. In other embodiments, the length ofcut fibers in the cut multicomponent fiber stream 101 is less than about25 mm, less than about 20 mm, less than about 15 mm, less than about 10mm, less than about 5 mm, or less than 2.5 mm.

The cut multicomponent fiber stream 101 and a portion of the treatedaqueous stream 103 are routed to a fiber slurry zone 200 to generate acut multicomponent fiber slurry 201 comprising water and cutmulticomponent fibers. In one embodiment, the weight % of cutmulticomponent fibers in the cut multicomponent fiber slurry 201 canrange from about 35 weight % to about 1% weight %, from about 25 weight% to about 1 weight %, from about 15 weight % to about 1 weight %, orfrom about 7 weight % to about 1 weight %.

The temperature of the cut multicomponent fiber slurry 201 can rangefrom about 5 degrees centigrade to about 45 degrees centigrade, fromabout 10 degrees centigrade to about 35 degrees centigrade, or fromabout 10 degrees centigrade to about 25 degrees centigrade. In oneembodiment, fiber slurry zone 200 comprises a tank with sufficientagitation to generate a suspension of cut multicomponent fiber in acontinuous aqueous phase.

Any equipment known in the art suitable for mixing a solid with waterand maintaining the resulting suspension of cut multicomponent fibers inthe continuous phase may be used in the fiber slurry zone 200. The fiberslurry zone 200 can comprise batch or continuous mixing devices operatedin continuous or batch mode. Suitable devices for use in the fiberslurry zone 200 include, but are not limited to, a hydro-pulper, acontinuous stirred tank reactor, a tank with agitation operated in batchmode.

The cut multicomponent fiber slurry 201 can then be routed to a fiberopening zone 400. One function of fiber opening zone 400 is to separatethe water dispersible polymer from the cut multicomponent fiber suchthat at least a portion of the water non-dispersible polymer microfibersseparate from the cut multicomponent fiber and become suspended in theopened microfiber slurry 401. In another embodiment of the invention,from about 50 weight % to about 100 weight % of water non-dispersiblepolymer microfiber contained in the cut multicomponent fiber slurry 201becomes suspended in the opened microfiber slurry 401 as waternon-dispersible polymer microfibers and is no longer a part of the cutmulticomponent fiber. In other embodiments, from about 75 weight % toabout 100 weight %, from about 90 weight % to about 100 weight %, orfrom about 95 weight % to about 100 weight % of the waternon-dispersible polymer microfiber contained in the cut multicomponentfiber stream 201 becomes suspended in the opened microfiber slurry 401as water non-dispersible polymer microfibers and are no longer a part ofa cut multicomponent fiber.

The diameter or denier of the starting cut multicomponent fiber instream 201 impacts the extent of separation of the water dispersiblesulfopolyester from the cut multicomponent fiber in the fiber openingzone 400. Typical multicomponent fiber types generally have a diameterin the range from about 12 microns to about 20 microns. Usefulmulticomponent fibers can have larger starting diameters to a size ofabout 40 microns diameter or more. The time required to separate adesired amount of water dispersible sulfopolyester from the cutmulticomponent fiber increases as the diameter of the cut multicomponentfiber in stream 201 increases.

Residence time, temperature, and shear forces in the fiber opening zone400 also influence the extent of separation of the water dispersiblesulfopolyester from the cut multicomponent fiber. The conditionsinfluencing the opening process in fiber opening zone 400 compriseresidence time, slurry temperature, and shear forces where the ranges ofwater temperature, residence time in the fiber opening zone 400, andamount of applied shear are dictated by the need to separate the waterdispersible sulfopolyester from the starting multicomponent fiber to asufficient degree to result in water non-dispersible polymer microfibersbecoming separated and suspended in the continuous aqueous phase of theopened microfiber slurry 401.

Residence time, temperature, and shear forces in fiber opening zone 400influence the extent of separation of the water dispersiblesulfopolyester from the cut multicomponent fiber. The temperature of thefiber opening zone 400 can range from about 55 degrees centigrade toabout 100 degrees centigrade, from about 60 degrees centigrade to about90 degrees centigrade, or from about 65 degrees centigrade to about 80degrees centigrade. The residence time in the fiber opening zone 400 canrange from about 5 minutes to about 10 seconds, from about 3 minutes toabout 20 seconds, or from about 2 minutes to about 30 seconds.Sufficient mixing is maintained in fiber opening zone 400 to maintain asuspension of cut water non-dispersible polymer microfibers such thatthe settling of the cut microfibers is minimal. In other embodiments ofthe invention, the mass per unit time of cut water non-dispersiblemicrofibers settling in the fiber opening zone 400 is less than about 5%of the mass per unit time of cut water non-dispersible polymermicrofibers entering the zone 400, less than about 3% of the mass perunit time of cut water non-dispersible polymer microfibers entering zone400, or less than about 1% of the mass per unit time of cut waternon-dispersible polymer microfibers entering the fiber opening zone 400.

Fiber opening in fiber opening zone 400 may be accomplished in anyequipment capable of allowing for acceptable ranges of residence time,temperature, and mixing. Examples of suitable equipment include, but arenot limited to, an agitated batch tank, a continuous stirred tankreactor, as shown in FIGS. 6 b and 6 c, and a pipe with sufficient flowto minimize solids from settling out of the slurry as shown in FIG. 6 a.One example of a unit operation to accomplish fiber opening in fiberopening zone 400 is a plug flow reactor where the heated multicomponentfiber slurry 301 is routed to zone 400 plug flow device, typically acircular pipe or conduit. The residence time of material in a plug flowdevice is calculated by dividing the filled volume within the device bythe volumetric flow rate in the device. Velocity of the mass in thedevice is defined by the cross sectional area of the flow channeldivided by the volumetric flow of the liquid through the device.

In other embodiments of the invention, the fiber opening zone 400 cancomprise a pipe or conduit wherein the velocity of mass flowing in thepipe can range from 0.1 ft/second to about 20 feet/second, from 0.2ft/sec to about 10 ft/sec, or from about 0.5 ft/sec to about 5 ft/sec.For flow of a fluid or slurry in a pipe or conduit, the Reynolds numberRe is a dimensionless number useful for describing the turbulence ormotion of fluid eddy currents that are irregular with respect both todirection and time. For flow in a pipe or tube, the Reynolds number isgenerally defined as:

${Re} = {\frac{\rho \; {vD}_{H}}{\mu} = {\frac{{vD}_{H}}{\nu} = \frac{{QD}_{H}}{\; {\nu \; A}}}}$

Where:

-   -   D_(H) is the hydraulic diameter of the pipe; L, (m).    -   Q is the volumetric flow rate (m³/s).    -   A is the pipe cross-sectional area (m²).    -   v is the mean velocity of the object relative to the fluid (SI        units: m/s).    -   μ is the dynamic viscosity of the fluid (Pa·s or N·s/m² or        kg/(m·s)).    -   v is the kinematic viscosity (v=μ/ρ) (m²/s).    -   ρ is the density of the fluid (kg/m³).        For flow in a pipe of diameter D, experimental observations show        that for fully developed flow, laminar flow occurs when        Re_(D)<2000, and turbulent flow occurs when Re_(D)>4000. In the        interval between 2300 and 4000, laminar and turbulent flows are        possible (‘transition’ flows), depending on other factors, such        as, pipe roughness and flow uniformity.

Fiber opening zone 400 can comprise a pipe or conduit to facilitate theopening process, and the Reynolds number for flow through the pipe orconduit in fiber opening zone 400 can range from about 2,100 to about6,000, from about 3,000 to about 6,000, or from about 3,500 to about6,000. In other embodiments, the fiber opening zone 400 can comprise apipe or conduit to facilitate the opening process, and the Reynoldsnumber for flow through the pipe or conduit is at least 2,500, at leastabout 3,500, or at least about 4,000.

Fiber opening zone 400 can be achieved in a pipe or conduit containing amixing device inserted within the pipe or conduit. The device cancomprise an in-line mixing device. The in-line mixing device can be astatic mixer with no moving parts. In another embodiment, the in-linemixing device comprises moving parts. Without being limiting, such anelement is a mechanical device for the purpose of imparting more mixingenergy to the heated multicomponent fiber slurry 301 than achieved bythe flow through the pipe. The device can be inserted at the beginningof the pipe section used as the fiber opening zone, at the end of thepipe section, or at any location within the pipe flow path.

The opened fiber slurry stream 401 comprising water non-dispersiblepolymer microfiber, water, and water dispersible sulfopolyester can berouted to a primary solid liquid separation zone 500 to generate amicrofiber product stream 503 comprising microfiber and a first motherliquor stream 501. In one embodiment, the first mother liquor stream 501comprises water and water dispersible sulfopolyester.

The weight % of solids in the opened microfiber slurry 401 can rangefrom about 0.1 weight % to about 20 weight %, from about 0.3 weight % toabout 10 weight %, from about 0.3 weight % to about 5 weight %, or fromabout 0.3 weight % to about 2.5 weight %.

The weight % of solids in the microfiber product stream 503 can rangefrom about 10 weight % to about 65 weight %, from about 15 weight % toabout 50 weight %, from about 25 weight % to about 45 weight %, or fromabout 30 weight % to about 40 weight %.

Separation of the microfiber product stream 503 from the openedmicrofiber slurry 401 can be accomplished by any method known in theart. In one embodiment, wash stream 103 comprising water is routed tothe primary solid liquid separation zone 500. Wash stream 103 can beused to wash the microfiber product stream in the primary solid liquidseparation zone 500 and/or the filter cloth media in the primary solidliquid separation zone 500 to generate wash liquor stream 502. A portionup to 100 weight % of wash liquor stream 502 can be combined with theopened microfiber slurry 401 prior to entering the primary solid liquidseparation zone 500. A portion up to 100 weight % of wash liquor stream502 can be routed to a second solid liquid separation zone 600. Washliquor stream 502 can contain microfiber. In one embodiment, the gramsof microfiber mass breaking though the filter media with openings up to2000 microns in the primary solid liquid separation zone 500 ranges fromabout 1 to 2 grams/cm² of filter area. In other embodiments of theinvention, the filter openings in the filter media in the primary solidliquid separation zone 500 can range from about 43 microns to 3000microns, from about 100 microns to 2000 microns, or from about 500microns to about 2000 microns.

Separation of the microfiber product stream from the opened microfiberslurry in primary solid liquid separation zone 500 may be accomplishedby a single or multiple solid liquid separation devices. Separation inthe primary solid liquid separation zone 500 may be accomplished by asolid liquid separation device or devices operated in batch and orcontinuous fashion. Suitable solid liquid separation devices in theprimary solid liquid separation zone 500 can include, but is not limitedto, at least one of the following: perforated basket centrifuges,continuous vacuum belt filters, batch vacuum nutschfilters, batchperforated settling tanks, twin wire dewatering devices, continuoushorizontal belt filters with a compressive zone, non vibrating inclinedscreen devices with wedge wire filter media, continuous vacuum drumfilters, dewatering conveyor belts, and the like.

In one embodiment, the primary solid liquid separation zone 500comprises a twin wire dewatering device wherein the opened microfibersturry 401 is routed to a tapering gap between a pair of travelingfilter cloths traveling in the same direction. In the first zone of thetwin wire dewatering device, water drains from the opened microfiberslurry 401 due to gravity and the every narrowing gap between the twomoving filter cloths. In a downstream zone of the twin wire dewateringdevice, the two filter cloths and the microfiber mass between the twofilter cloths are compressed one or more times to mechanically reducemoisture in the microfiber mass. In one embodiment, mechanicaldewatering is accomplished by passing the two filter cloths andcontained microfiber mass through at least one set of rollers that exerta compressive force on the two filter cloths and microfiber massbetween. In another embodiment, mechanical dewatering is accomplished bypassing the two filter cloths and microfiber mass between at least oneset of pressure rollers.

In other embodiments of the invention, the force exerted by mechanicaldewatering for each set of pressure rollers can range from about 25 toabout 300 lbs/linear inch of filter media width, from about 50 to about200 lbs/linear inch of filter media width, or from about 70 to about 125lbs/linear inch of filter media width. The microfiber product stream 503is discharged from the twin wire water dewatering device as the twofilter cloths separate and diverge at the solids discharge zone of thedevice. The thickness of the discharged microfiber mass can range fromabout 0.2 inches to about 1.5 inches, from about 0.3 inches to about1.25 inches, or from about 0.4 inches to about 1 inch. In oneembodiment, a wash stream comprising water is continuously applied tothe filter media. In another embodiment, a wash stream comprising wateris periodically applied to the filter media.

In another embodiment, the primary solid liquid separation zone 500comprises a belt filter device comprising a gravity drainage zone and apressure dewatering zone as illustrated in FIG. 7. Opened microfiberslurry 401 is routed to a tapering gap between a pair of moving filtercloths traveling in the same direction which first pass through agravity drainage zone and then pass through a pressure dewatering zoneor press zone comprising a convoluted arrangement of rollers asillustrated in FIG. 6 b. As the belts are fed through the rollers, wateris squeezed out of the solids. When the belts pass through the finalpair of rollers in the process, the filter cloths are separated and thesolids exit the belt filter device.

In another embodiment of the invention, at least a portion of the watercontained in the first mother liquor stream 501 comprising water andwater dispersible sulfopolyester polymer is recovered and recycled. Thefirst mother liquor stream 501 can be recycled to the primary solidliquid separation zone 500. Depending on the efficiency of the primaryliquid separation zone in the removal of the water non-dispersiblemicrofiber, the first mother liquid stream 501 can be recycled to thefiber slurry zone 200, the fiber opening zone 400, or the heat exchangerzone 800 prior to being routed to Zones 200 and/or 400. The first motherliquor stream 501 can contain a small amount of solids comprising waternon-dispersible polymer microfiber due to breakthrough and cloth wash.In one embodiment, the grams of water non-dispersible polymer microfibermass breaking though filter media in the primary solid liquid separationzone with openings up to 2000 microns ranges from about 1 to about 2grams/cm² of filter area. It is desirable to minimize the waternon-dispersible polymer microfiber solids in the first mother liquorstream 501 prior to routing stream 501 to the primary concentration zone700 and heat exchange zone 800 where water non-dispersible polymermicrofiber solids can collect and accumulate in the zones having anegative impact on their function.

A secondary solid liquid separation zone 600 can serve to remove atleast a portion of water non-dispersible polymer microfiber solidspresent in the first mother liquor stream 501 to generate a secondarywet cake stream 602 comprising water non-dispersible microfiber and asecond mother liquor stream 601 comprising water and water dispersiblesulfopolyester.

In one embodiment, the second mother liquor stream 601 can be routed toa primary concentration zone 700 and or heat exchanger zone 800 whereinthe weight % of the second mother liquor stream 601 routed to theprimary concentration zone 700 can range from 0% to 100% with thebalance of the stream being routed to heat exchanger zone 800. Thesecond mother liquor stream 601 can be recycled to the fiber slurry zone200, the fiber opening zone 400, or the heat exchanger zone 800 prior tobeing routed to Zones 200 and/or 400. The amount of the waterdispersible sulfopolyester in the second mother liquor stream routed tothe fiber opening zone 400 can range from about 0.01 weight % to about 7weight %, based on the weight % of the second mother liquor stream, orfrom about 0.1 weight % to about 7 weight %, from about 0.2 weight % toabout 5 weight %, or from about 0.3 weight % to about 3 weight %.

Any portion of the second mother liquor 601 routed to primaryconcentration zone is subjected to a separation process to generate aprimary recovered water stream 703 and a primary polymer concentratestream 702 enriched in water dispersible sulfopolyester wherein theweight % of water dispersible sulfopolyester in the primary polymerconcentrate stream 702 can range from about 5 weight % to about 85%,from about 10 weight % to about 65 weight %, or from about 15 weight %to about 45 weight %. The primary recovered water stream 703 can berecycled to the fiber slurry zone 200, the fiber opening zone 400, orthe heat exchanger zone 800 prior to being routed to Zones 200 and/or400. The amount of the water dispersible sulfopolyester in the secondmother liquor stream routed to the fiber opening zone 400 can range fromabout 0.01 weight % to about 7 weight %, based on the weight % of thesecond mother liquor stream, or from about 0.1 weight % to about 7weight %, from about 0.2 weight % to about 5 weight %, or from about 0.3weight % to about 3 weight %.

Water can be removed from the second mother liquor stream 601 by anymethod know in the art in the primary concentration zone 700 to producethe primary polymer concentrate stream 702. In one embodiment, removalof water involves an evaporative process by boiling water away in batchor continuous evaporative equipment. For example, at least one thin filmevaporator can be used for this application. In another embodiment,membrane technology comprising nanofiltration media can be used togenerate the primary polymer concentrate stream 702. In anotherembodiment, a process comprising extraction equipment may be used toextract water dispersible polymer from the second mother liquor stream601 and generate the primary polymer concentrate stream 702. It isunderstood than any combination of evaporation, membrane, and extractionsteps may be used to separate the water dispersible sulfopolyester fromthe second mother liquor stream 601 and generate the primary polymerconcentrate stream 702. The primary polymer concentration stream 702 maythen exit the process.

In one embodiment, the primary polymer concentrate stream 702 can berouted to a secondary concentration zone 900 to generate a meltedpolymer stream 903 comprising water dispersible sulfopolyester whereinthe weight % of polymer ranges from about 95% to about 100% and a vaporstream 902 comprising water. In one embodiment, the 903 comprises waterdispersible sulfopolyester. Equipment suitable for the secondaryconcentration zone 900 includes any equipment known in the art capableof being fed an aqueous dispersion of water dispersible polymer andgenerating a 95% to 100% water dispersible polymer stream 903. Thisembodiment comprises feeding an aqueous dispersion of water dispersiblesulfopolyester polymer to a secondary concentration zone 902. Thetemperature of feed stream is typically below 100° C.

In one embodiment, the secondary concentration zone 900 comprises atleast one device characterized by a jacketed tubular shell containing arotating convey screw wherein the convey screw is heated with a heattransfer fluid or steam and comprises both convey and high shear mixingelements. The jacket or shell is vented to allow for vapor to escape.The shell jacket may be zoned to allow for different temperature setpoints along the length of the device. During continuous operation, theprimary polymer concentrate stream 702 comprises water and waterdispersible sulfopolyester and is continuously fed to the secondaryconcentration zone 900. Within the device, during steady state, massexists in at least three distinct and different forms. Mass first existsin the device as an aqueous dispersion of water dispersiblesulfopolyester polymer. As the aqueous dispersion of sulfopolyesterpolymer moves through the device, water is evaporated due to the heat ofthe jacket and internal screw. When sufficient water is evaporated, themass becomes a second form comprising a viscous plug at a temperatureless than the melt temperature of the sulfopolyester polymer. Theaqueous dispersion cannot flow past this viscous plug and is confined tothe first aqueous dispersion zone of the device. Due to the heat of thejacket, heat of the internally heated screw, and the heat due to mixingshear forces of this high viscosity plug mass, substantially all thewater present at this location evaporates, and the temperature risesuntil the melt temperature of the sulfopolyester is reached resulting inthe third and final physical form of mass in the device comprisingmelted sulfopolyester polymer. The melted sulfopolyester polymer thenexits the device through an extrusion dye and is typically cooled andcut into pellets by any fashion know in the art. It is understood thatthe device for secondary concentration zone 900 described above may alsobe operated in batch fashion wherein the three physical forms of massdescribed above occur throughout the length of the device but atdifferent times in sequential order beginning with the aqueousdispersion, the viscous plug mass, and finally the sulfopolyester melt.

In one embodiment, vapor generated in the secondary concentration zone900 may be condensed and routed to heat exchanger zone 800, discarded,and/or routed to wash stream 103. In another embodiment, condensed vaporstream 902 comprising water vapor can be routed to heat exchanger zone800 to provide at least part of the energy required for generating therequired temperature for stream 801. The melted polymer stream 903comprising water dispersible polymer comprising sulfopolyester in themelt phase can be cooled and chopped into pellets by any method known inthe art.

Impurities can enter the process and concentrated in water recovered andrecycled. One or more purge streams (603 and 701) can be utilized tocontrol the concentration of impurities in the second mother liquor 601and primary recovered water stream 701 to acceptable levels. In oneembodiment, a portion of the second mother liquor stream 601 can beisolated and purged from the process. In one embodiment, a portion ofthe primary recovered water stream 701 can be isolated and purged fromthe process.

In another embodiment of the invention, as shown in FIG. 3 b, a processfor producing a microfiber product stream is provided. The processcomprises:

(A) contacting short cut multicomponent fibers 101 having a length ofless than 25 millimeters with a heated aqueous stream 801 in a mix zoneto produce a short cut multicomponent fiber slurry 301; wherein theshort cut multicomponent fibers 101 comprise at least one waterdispersible sulfopolyester and at least one water non-dispersiblepolymer immiscible with the water dispersible sulfopolyester; andwherein the heated aqueous stream 801 is at a temperature of 40° C. orgreater;

(B) routing the short cut multicomponent fiber slurry 301 andoptionally, a heated aqueous stream 801, to a fiber opening zone 400 toremove a portion of the water dispersible sulfopolyester to produce anopened microfiber slurry 401; wherein the opened microfiber slurry 401comprises water non-dispersible polymer microfiber, water dispersiblesulfopolyester, and water; and

(C) routing the opened microfiber slurry 401 to a primary solid liquidseparation zone 500 to produce the microfiber product stream 503 and afirst mother liquor stream 501; wherein the first mother liquor stream501 comprises water and the water dispersible sulfopolyester.

In this embodiment of the invention as shown in FIG. 3 b, the fiberslurry zone 200 and the fiber mix zone 300 have been combined into oneunit operation in the opening process zone 1100. The opening processzone 1100 comprises a mix zone 200 and a fiber opening zone 400.

A treated aqueous stream 103 for use in the process can be produced byrouting an aqueous stream 102 to an aqueous treatment zone 1000 toproduce a treated aqueous stream 103. The aqueous stream compriseswater. In embodiments of the invention, the concentration of monovalentmetal cations in the treated aqueous stream 103 can be less than about1000 ppm by weight, less than about 500 ppm by weight, less than about100 ppm by weight, or less than about 50 ppm by weight. Removal ofdivalent and multivalent metal cations from the aqueous stream 102 isone function of the aqueous treatment zone 1000. In other embodiments ofthe invention, the concentration of divalent and multivalent cations isless than about 50 ppm by weight, less than about 25 ppm by weight, lessthan about 10 ppm by weight, or less than about 5 ppm by weight. Thetemperature of stream 103 can range from ground water temperature toabout 40° C.

The treatment of the aqueous stream 102 in the aqueous treatment zone1000 can be accomplished in any way know in the art. In one embodiment,aqueous treatment zone 1000 comprises distillation equipment whereinwater vapor is generated and condensed to produce the treated aqueousstream 103. In another embodiment, water is routed to a reverse osmosismembrane separation capable of separating monovalent and divalent metalcations from water to produce the treated aqueous stream 103. In anotherembodiment, water is routed to an ion exchange resin to generate thetreated aqueous stream 103 with acceptably low concentration of metalcations. In yet another embodiment, water can be routed to a commercialwater softening apparatus to generate the treated aqueous stream 103with an acceptably low concentration of divalent and multivalent metalcations. It is understood that any combinations of these water treatmentoptions may be employed to achieve the required treated watercharacteristics.

The treated aqueous stream 103 may be routed to any location in theprocess where it is needed. In one embodiment, a portion of stream 103is routed to a primary solid liquid separation zone 500 to serve as acloth wash and/or a wash for solids contained in the primary solidliquid separation zone 500.

In one embodiment, at least a portion of the treated aqueous stream 103is routed to heat exchanger zone 800. In another embodiment, at least aportion of treated aqueous stream 103 is routed to a mix zone 300. Inanother embodiment, at least a portion of the treated aqueous stream 103is routed to heat exchanger zone 800 and at least a portion of thetreated aqueous stream 103 is routed to the mix zone 300. One functionof heat exchanger zone 800 is to generate a heated aqueous stream 801 ata specific and controlled temperature.

In one embodiment, streams that can feed heat exchanger zone 800 are thetreated aqueous stream 103 and the second mother liquor stream 601. Inanother embodiment, streams that can feed heat exchanger zone 800comprise the treated aqueous stream 103, the primary recovered waterstream 703, the first mother liquor stream 501, and the second motherliquor stream 601.

Any equipment know in the art for controlling the temperature of stream801 may be used including, but not limited to, any heat exchanger withsteam used to provide a portion of the required energy, any heatexchanger with a heat transfer fluid used to provide a portion of therequired energy, any heat exchanger with electrical heating elementsused to provide a portion of the required energy, and any vessel or tankwith direct steam injection wherein the steam condenses and thecondensate mixes with the water feeds to heat exchanger zone 800. Themulticomponent fiber stream 90 is routed to fiber cutting zone 100 togenerate cut multicomponent fiber stream 101. The multicomponent fibercan be of any multicomponent structure known in the art. Themulticomponent fiber comprises a water dispersible sulfopolyester and awater non-dispersible polymer as previously discussed in thisdisclosure.

Any equipment know in the art may be used to cut multicomponent fiberstream 90 to generate cut multicomponent fiber stream 101. In oneembodiment, the length of the cut fibers in the cut multicomponent fiberstream 101 is less than about 50 mm. In other embodiments, the length ofcut fibers in the cut multicomponent fiber stream 101 is less than about25 mm, less than about 20 mm, less than about 15 mm, less than about 10mm, less than about 5 mm, or less than 2.5 mm.

The cut multicomponent fiber stream 101 and a portion of the heatedaqueous stream 801 are routed to a mix zone 300 to generate a heatedmulticomponent fiber slurry 301 comprising water and cut multicomponentfibers

The temperature of the heated multicomponent fiber slurry 301 influencesthe separation of the water dispersible sulfopolyester portion of thecut multicomponent fiber from the water non-dispersible polymer portionof the cut multicomponent fiber in fiber opening zone 400. In otherembodiments of the invention, the temperature of the heatedmulticomponent fiber slurry 301 can range from about 55 degreescentigrade to about 100 degrees centigrade, from about 60 degreescentigrade to about 90 degrees centigrade, or from about 65 degreescentigrade to about 80 degrees centigrade.

The weight % of cut multicomponent fiber in the heated multicomponentfiber slurry 301 can be controlled. In other embodiments, the weight %of cut multicomponent fibers in the heated multicomponent fiber slurry301 can range from about 10 weight % to about 0.1% weight %, from about5 weight % to about 0.2 weight %, from about 3 weight % to about 0.3weight %, or from about 2 weight % to about 0.4 weight %.

Any device known in the art capable of mixing the heated aqueous stream801 with the cut multicomponent fibers 101 may be used in mix zone 300.Suitable devices include both continuous and batch mixing devices. Inone embodiment, a suitable mixing device for mix zone 300 comprises atank and an agitator. In another embodiment, a suitable mixing devicecomprises a pipe or conduit.

In other embodiments, a suitable mixing device in mix zone 300 comprisesa pipe or conduit with a diameter such that the speed in the conduit issufficient to mix the cut multicomponent fiber slurry 201 and the heatedaqueous stream 801 wherein less than about 2 weight %, less than about 1weight %, or less than about 0.5 weight of cut multicomponent massentering the conduit per minute settles out and accumulates in theconduit.

The heated multicomponent fiber slurry 301 can then be routed to a fiberopening zone 400. One function of fiber opening zone 400 is to separatethe water dispersible polymer from the cut multicomponent fiber suchthat at least a portion of the water non-dispersible polymer microfibersseparate from the cut multicomponent fiber and become suspended in theopened microfiber slurry 401. In another embodiment of the invention,from about 50 weight % to about 100 weight % of water non-dispersiblepolymer microfiber contained in the cut multicomponent fiber slurry 201becomes suspended in the opened microfiber slurry 401 as waternon-dispersible polymer microfibers and is no longer a part of the cutmulticomponent fiber. In other embodiments, from about 75 weight % toabout 100 weight %, from about 90 weight % to about 100 weight %, orfrom about 95 weight % to about 100 weight % of the waternon-dispersible polymer microfiber contained in the cut multicomponentfiber stream 201 becomes suspended in the opened microfiber slurry 401as water non-dispersible polymer microfibers and are no longer a part ofa cut multicomponent fiber.

The diameter or denier of the starting cut multicomponent fiber instream 201 impacts the extent of separation of the water dispersiblesulfopolyester from the cut multicomponent fiber in the fiber openingzone 400. Typical multicomponent fiber types generally have a diameterin the range from about 12 microns to about 20 microns. Usefulmulticomponent fibers can have larger starting diameters to a size ofabout 40 microns diameter or more. The time required to separate adesired amount of water dispersible sulfopolyester from the cutmulticomponent fiber increases as the diameter of the cut multicomponentfiber in stream 201 increases.

Residence time, temperature, and shear forces in the fiber opening zone400 also influence the extent of separation of the water dispersiblesulfopolyester from the cut multicomponent fiber. The conditionsinfluencing the opening process in fiber opening zone 400 compriseresidence time, slurry temperature, and shear forces where the ranges ofwater temperature, residence time in the fiber opening zone 400, andamount of applied shear are dictated by the need to separate the waterdispersible sulfopolyester from the starting multicomponent fiber to asufficient degree to result in water non-dispersible polymer microfibersbecoming separated and suspended in the continuous aqueous phase of theopened microfiber slurry 401.

Residence time, temperature, and shear forces in fiber opening zone 400influence the extent of separation of the water dispersiblesulfopolyester from the cut multicomponent fiber. The temperature of thefiber opening zone 400 can range from about 55 degrees centigrade toabout 100 degrees centigrade, from about 60 degrees centigrade to about90 degrees centigrade, or from about 65 degrees centigrade to about 80degrees centigrade. The residence time in the fiber opening zone 400 canrange from about 5 minutes to about 10 seconds, from about 3 minutes toabout 20 seconds, or from about 2 minutes to about 30 seconds.Sufficient mixing is maintained in fiber opening zone 400 to maintain asuspension of cut water non-dispersible polymer microfibers such thatthe settling of the cut microfibers is minimal. In other embodiments ofthe invention, the mass per unit time of cut water non-dispersiblemicrofibers settling in the fiber opening zone 400 is less than about 5%of the mass per unit time of cut water non-dispersible polymermicrofibers entering the zone 400, less than about 3% of the mass perunit time of cut water non-dispersible polymer microfibers entering zone400, or less than about 1% of the mass per unit time of cut waternon-dispersible polymer microfibers entering the fiber opening zone 400.

Fiber opening in fiber opening zone 400 may be accomplished in anyequipment capable of allowing for acceptable ranges of residence time,temperature, and mixing. Examples of suitable equipment include, but arenot limited to, an agitated batch tank, a continuous stirred tankreactor, as shown in FIGS. 6 b and 6 c, and a pipe with sufficient flowto minimize solids from settling out of the slurry as shown in FIG. 6 a.One example of a unit operation to accomplish fiber opening in fiberopening zone 400 is a plug flow reactor where the heated multicomponentfiber slurry 301 is routed to zone 400 plug flow device, typically acircular pipe or conduit. The residence time of material in a plug flowdevice is calculated by dividing the filled volume within the device bythe volumetric flow rate in the device. Velocity of the mass in thedevice is defined by the cross sectional area of the flow channeldivided by the volumetric flow of the liquid through the device.

In other embodiments of the invention, the fiber opening zone 400 cancomprise a pipe or conduit wherein the velocity of mass flowing in thepipe can range from 0.1 ft/second to about 20 feet/second, from 0.2ft/sec to about 10 ft/sec, or from about 0.5 ft/sec to about 5 ft/sec.For flow of a fluid or slurry in a pipe or conduit, the Reynolds numberRe is a dimensionless number useful for describing the turbulence ormotion of fluid eddy currents that are irregular with respect both todirection and time. For flow in a pipe or tube, the Reynolds number isgenerally defined as:

${Re} = {\frac{\rho \; {vD}_{H}}{\mu} = {\frac{{vD}_{H}}{\nu} = \frac{{QD}_{H}}{\; {\nu \; A}}}}$

Where:

-   -   D_(H) is the hydraulic diameter of the pipe; L, (m).    -   Q is the volumetric flow rate (m³/s).    -   A is the pipe cross-sectional area (m²).    -   v is the mean velocity of the object relative to the fluid (SI        units: m/s).    -   μ is the dynamic viscosity of the fluid (Pa·s or N·s/m² or        kg/(m·s)).    -   v is the kinematic viscosity (v=μ/ρ) (m²/s).    -   ρ is the density of the fluid (kg/m³).        For flow in a pipe of diameter D, experimental observations show        that for fully developed flow, laminar flow occurs when        Re_(D)<2000, and turbulent flow occurs when Re_(D)>4000. In the        interval between 2300 and 4000, laminar and turbulent flows are        possible (‘transition’ flows), depending on other factors, such        as, pipe roughness and flow uniformity.

Fiber opening zone 400 can comprise a pipe or conduit to facilitate theopening process, and the Reynolds number for flow through the pipe orconduit in fiber opening zone 400 can range from about 2,100 to about6,000, from about 3,000 to about 6,000, or from about 3,500 to about6,000. In other embodiments, the fiber opening zone 400 can comprise apipe or conduit to facilitate the opening process, and the Reynoldsnumber for flow through the pipe or conduit is at least 2,500, at leastabout 3,500, or at least about 4,000.

Fiber opening zone 400 can be achieved in a pipe or conduit containing amixing device inserted within the pipe or conduit. The device cancomprise an in-line mixing device. The in-line mixing device can be astatic mixer with no moving parts. In another embodiment, the in-linemixing device comprises moving parts. Without being limiting, such anelement is a mechanical device for the purpose of imparting more mixingenergy to the heated multicomponent fiber slurry 301 than achieved bythe flow through the pipe. The device can be inserted at the beginningof the pipe section used as the fiber opening zone, at the end of thepipe section, or at any location within the pipe flow path.

The opened fiber slurry stream 401 comprising water non-dispersiblepolymer microfiber, water, and water dispersible sulfopolyester can berouted to a primary solid liquid separation zone 500 to generate amicrofiber product stream 503 comprising microfiber and a first motherliquor stream 501. In one embodiment, the first mother liquor stream 501comprises water and water dispersible sulfopolyester.

The weight % of solids in the opened microfiber slurry 401 can rangefrom about 0.1 weight % to about 20 weight %, from about 0.3 weight % toabout 10 weight %, from about 0.3 weight % to about 5 weight %, or fromabout 0.3 weight % to about 2.5 weight %.

The weight % of solids in the microfiber product stream 503 can rangefrom about 10 weight % to about 65 weight %, from about 15 weight % toabout 50 weight %, from about 25 weight % to about 45 weight %, or fromabout 30 weight % to about 40 weight %.

Separation of the microfiber product stream 503 from the openedmicrofiber slurry 401 can be accomplished by any method known in theart. In one embodiment, wash stream 103 comprising water is routed tothe primary solid liquid separation zone 500. Wash stream 103 can beused to wash the microfiber product stream in the primary solid liquidseparation zone 500 and/or the filter cloth media in the primary solidliquid separation zone 500 to generate wash liquor stream 502. A portionup to 100 weight % of wash liquor stream 502 can be combined with theopened microfiber slurry 401 prior to entering the primary solid liquidseparation zone 500. A portion up to 100 weight % of wash liquor stream502 can be routed to a second solid liquid separation zone 600. Washliquor stream 502 can contain microfiber. In one embodiment, the gramsof microfiber mass breaking though the filter media with openings up to2000 microns in the primary solid liquid separation zone 500 ranges fromabout 1 to 2 grams/cm² of filter area. In other embodiments of theinvention, the filter openings in the filter media in the primary solidliquid separation zone 500 can range from about 43 microns to 3000microns, from about 100 microns to 2000 microns, or from about 500microns to about 2000 microns.

Separation of the microfiber product stream from the opened microfiberslurry in primary solid liquid separation zone 500 may be accomplishedby a single or multiple solid liquid separation devices. Separation inthe primary solid liquid separation zone 500 may be accomplished by asolid liquid separation device or devices operated in batch and orcontinuous fashion. Suitable solid liquid separation devices in theprimary solid liquid separation zone 500 can include, but is not limitedto, at least one of the following: perforated basket centrifuges,continuous vacuum belt filters, batch vacuum nutschfilters, batchperforated settling tanks, twin wire dewatering devices, continuoushorizontal belt filters with a compressive zone, non vibrating inclinedscreen devices with wedge wire filter media, continuous vacuum drumfilters, dewatering conveyor belts, and the like.

In one embodiment, the primary solid liquid separation zone 500comprises a twin wire dewatering device wherein the opened microfibersturry 401 is routed to a tapering gap between a pair of travelingfilter cloths traveling in the same direction. In the first zone of thetwin wire dewatering device, water drains from the opened microfiberslurry 401 due to gravity and the every narrowing gap between the twomoving filter cloths. In a downstream zone of the twin wire dewateringdevice, the two filter cloths and the microfiber mass between the twofilter cloths are compressed one or more times to mechanically reducemoisture in the microfiber mass. In one embodiment, mechanicaldewatering is accomplished by passing the two filter cloths andcontained microfiber mass through at least one set of rollers that exerta compressive force on the two filter cloths and microfiber massbetween. In another embodiment, mechanical dewatering is accomplished bypassing the two filter cloths and microfiber mass between at least onepressure roller and a fixed surface.

In other embodiments of the invention, the force exerted by mechanicaldewatering can range from about 25 to about 300 lbs/linear inch offilter media width, from about 50 to about 200 lbs/linear inch of filtermedia width, or from about 70 to about 125 lbs/linear inch of filtermedia width. The microfiber product stream 503 is discharged from thetwin wire water dewatering device as the two filter cloths separate anddiverge at the solids discharge zone of the device. The thickness of thedischarged microfiber mass can range from about 0.2 inches to about 1.5inches, from about 0.3 inches to about 1.25 inches, or from about 0.4inches to about 1 inch. In one embodiment, a wash stream comprisingwater is continuously applied to the filter media. In anotherembodiment, a wash stream comprising water is periodically applied tothe filter media.

In another embodiment, the primary solid liquid separation zone 500comprises a belt filter device comprising a gravity drainage zone and apressure dewatering zone as illustrated in FIG. 7. Opened microfiberslurry 401 is routed to a tapering gap between a pair of moving filtercloths traveling in the same direction which first pass through agravity drainage zone and then pass through a pressure dewatering zoneor press zone comprising a convoluted arrangement of rollers asillustrated in FIG. 6 b. As the belts are fed through the rollers, wateris squeezed out of the solids. When the belts pass through the finalpair of rollers in the process, the filter cloths are separated and thesolids exit the belt filter device.

In another embodiment of the invention, at least a portion of the watercontained in the first mother liquor stream 501 comprising water andwater dispersible sulfopolyester polymer is recovered and recycled. Thefirst mother liquor stream 501 can be recycled to the primary solidliquid separation zone 500. Depending on the efficiency of the primaryliquid separation zone in the removal of the water non-dispersiblemicrofiber, the first mother liquid stream 501 can be recycled to themix zone 300, the fiber opening zone 400, or the heat exchanger zone 800prior to being routed to Zones 200, 300 and/or 400. The first motherliquor stream 501 can contain a small amount of solids comprising waternon-dispersible polymer microfiber due to breakthrough and cloth wash.In one embodiment, the grams of water non-dispersible polymer microfibermass breaking though filter media in the primary solid liquid separationzone with openings up to 2000 microns ranges from about 1 to about 2grams/cm² of filter area. It is desirable to minimize the waternon-dispersible polymer microfiber solids in the first mother liquorstream 501 prior to routing stream 501 to the primary concentration zone700 and heat exchange zone 800 where water non-dispersible polymermicrofiber solids can collect and accumulate in the zones having anegative impact on their function.

A secondary solid liquid separation zone 600 can serve to remove atleast a portion of water non-dispersible polymer microfiber solidspresent in the first mother liquor stream 501 to generate a secondarywet cake stream 602 comprising water non-dispersible microfiber and asecond mother liquor stream 601 comprising water and water dispersiblesulfopolyester.

In one embodiment, the second mother liquor stream 601 can be routed toa primary concentration zone 700 and or heat exchanger zone 800 whereinthe weight % of the second mother liquor stream 601 routed to theprimary concentration zone 700 can range from 0% to 100% with thebalance of the stream being routed to heat exchanger zone 800. Thesecond mother liquor stream 601 can be recycled to the fiber slurry zone200, the mix zone 300, the fiber opening zone 400, or the heat exchangerzone 800 prior to being routed to Zones 200, 300 and/or 400. The amountof the water dispersible sulfopolyester in the second mother liquorstream routed to the fiber opening zone 400 can range from about 0.01weight % to about 7 weight %, based on the weight % of the second motherliquor stream, or from about 0.1 weight % to about 7 weight %, fromabout 0.2 weight % to about 5 weight %, or from about 0.3 weight % toabout 3 weight %.

Any portion of the second mother liquor 601 routed to primaryconcentration zone is subjected to a separation process to generate aprimary recovered water stream 703 and a primary polymer concentratestream 702 enriched in water dispersible sulfopolyester wherein theweight % of water dispersible sulfopolyester in the primary polymerconcentrate stream 702 can range from about 5 weight % to about 85%,from about 10 weight % to about 65 weight %, or from about 15 weight %to about 45 weight %. The primary recovered water stream 703 can be themix zone 300, the fiber opening zone 400, or the heat exchanger zone 800prior to being routed to Zones 200, 300 and/or 400. The amount of thewater dispersible sulfopolyester in the second mother liquor streamrouted to the fiber opening zone 400 can range from about 0.01 weight %to about 7 weight %, based on the weight % of the second mother liquorstream, or from about 0.1 weight % to about 7 weight %, from about 0.2weight % to about 5 weight %, or from about 0.3 weight % to about 3weight %.

Water can be removed from the second mother liquor stream 601 by anymethod know in the art in the primary concentration zone 700 to producethe primary polymer concentrate stream 702. In one embodiment, removalof water involves an evaporative process by boiling water away in batchor continuous evaporative equipment. For example, at least one thin filmevaporator can be used for this application. In another embodiment,membrane technology comprising nanofiltration media can be used togenerate the primary polymer concentrate stream 702. In anotherembodiment, a process comprising extraction equipment may be used toextract water dispersible polymer from the second mother liquor stream601 and generate the primary polymer concentrate stream 702. It isunderstood than any combination of evaporation, membrane, and extractionsteps may be used to separate the water dispersible sulfopolyester fromthe second mother liquor stream 601 and generate the primary polymerconcentrate stream 702. The primary polymer concentration stream 702 maythen exit the process.

In one embodiment, the primary polymer concentrate stream 702 can berouted to a secondary concentration zone 900 to generate a meltedpolymer stream 903 comprising water dispersible sulfopolyester whereinthe weight % of polymer ranges from about 95% to about 100% and a vaporstream 902 comprising water. In one embodiment, the 903 comprises waterdispersible sulfopolyester. Equipment suitable for the secondaryconcentration zone 900 includes any equipment known in the art capableof being fed an aqueous dispersion of water dispersible polymer andgenerating a 95% to 100% water dispersible polymer stream 903. Thisembodiment comprises feeding an aqueous dispersion of water dispersiblesulfopolyester polymer to a secondary concentration zone 902. Thetemperature of feed stream is typically below 100° C.

In one embodiment, the secondary concentration zone 900 comprises atleast one device characterized by a jacketed tubular shell containing arotating convey screw wherein the convey screw is heated with a heattransfer fluid or steam and comprises both convey and high shear mixingelements. The jacket or shell is vented to allow for vapor to escape.The shell jacket may be zoned to allow for different temperature setpoints along the length of the device. During continuous operation, theprimary polymer concentrate stream 702 comprises water and waterdispersible sulfopolyester and is continuously fed to the secondaryconcentration zone 900. Within the device, during steady state, massexists in at least three distinct and different forms. Mass first existsin the device as an aqueous dispersion of water dispersiblesulfopolyester polymer. As the aqueous dispersion of sulfopolyesterpolymer moves through the device, water is evaporated due to the heat ofthe jacket and internal screw. When sufficient water is evaporated, themass becomes a second form comprising a viscous plug at a temperatureless than the melt temperature of the sulfopolyester polymer. Theaqueous dispersion cannot flow past this viscous plug and is confined tothe first aqueous dispersion zone of the device. Due to the heat of thejacket, heat of the internally heated screw, and the heat due to mixingshear forces of this high viscosity plug mass, substantially all thewater present at this location evaporates, and the temperature risesuntil the melt temperature of the sulfopolyester is reached resulting inthe third and final physical form of mass in the device comprisingmelted sulfopolyester polymer. The melted sulfopolyester polymer thenexits the device through an extrusion dye and is typically cooled andcut into pellets by any fashion know in the art. It is understood thatthe device for secondary concentration zone 900 described above may alsobe operated in batch fashion wherein the three physical forms of massdescribed above occur throughout the length of the device but atdifferent times in sequential order beginning with the aqueousdispersion, the viscous plug mass, and finally the sulfopolyester melt.

In one embodiment, vapor generated in the secondary concentration zone900 may be condensed and routed to heat exchanger zone 800, discarded,and/or routed to wash stream 103. In another embodiment, condensed vaporstream 902 comprising water vapor can be routed to heat exchanger zone800 to provide at least part of the energy required for generating therequired temperature for stream 801. The melted polymer stream 903comprising water dispersible polymer comprising sulfopolyester in themelt phase can be cooled and chopped into pellets by any method known inthe art.

Impurities can enter the process and concentrated in water recovered andrecycled. One or more purge streams (603 and 701) can be utilized tocontrol the concentration of impurities in the second mother liquor 601and primary recovered water stream 701 to acceptable levels. In oneembodiment, a portion of the second mother liquor stream 601 can beisolated and purged from the process. In one embodiment, a portion ofthe primary recovered water stream 701 can be isolated and purged fromthe process.

In another embodiment of the invention, as shown in FIG. 4, a processfor producing a microfiber product stream is provided. The processcomprises:

(A) contacting short cut multicomponent fibers 101 having a length ofless than 25 millimeters with a treated aqueous stream 103 in a fiberslurry zone 200 to produce a short cut multicomponent fiber slurry 201;wherein the short cut multicomponent fibers 101 comprise at least onewater dispersible sulfopolyester and at least one water non-dispersiblesynthetic polymer immiscible with the water dispersible sulfopolyester;and wherein the treated aqueous stream 103 is at a temperature of lessthan 40° C.;(B) contacting the short cut multicomponent fiber slurry 201 with aheated aqueous stream 801 in a mix zone 300 to produce a heatedmulticomponent fiber slurry 301;(C) routing the heated multicomponent fiber slurry 301 to a fiberopening zone 400 to remove a portion of the water dispersiblesulfopolyester to produce an opened microfiber slurry 401; and(D) routing the opened microfiber slurry 401 to a primary solid liquidseparation zone 500 to produce the microfiber product stream 503 and afirst mother liquor stream 501; wherein the first mother liquor stream501 comprises water and the water dispersible sulfopolyester.

In this embodiment of the invention as shown in FIG. 4, the openingprocess zone 1100 comprises a fiber slurry zone 200, mix zone 300 and afiber opening zone 400.

A treated aqueous stream 103 for use in the process can be produced byrouting an aqueous stream 102 to an aqueous treatment zone 1000 toproduce a treated aqueous stream 103. The aqueous stream compriseswater. In embodiments of the invention, the concentration of monovalentmetal cations in the treated aqueous stream 103 can be less than about1000 ppm by weight, less than about 500 ppm by weight, less than about100 ppm by weight, or less than about 50 ppm by weight. Removal ofdivalent and multivalent metal cations from the aqueous stream 102 isone function of the aqueous treatment zone 1000. In other embodiments ofthe invention, the concentration of divalent and multivalent cations isless than about 50 ppm by weight, less than about 25 ppm by weight, lessthan about 10 ppm by weight, or less than about 5 ppm by weight. Thetemperature of stream 103 can range from ground water temperature toabout 40° C.

The treatment of the aqueous stream 102 in the aqueous treatment zone1000 can be accomplished in any way know in the art. In one embodiment,aqueous treatment zone 1000 comprises distillation equipment whereinwater vapor is generated and condensed to produce the treated aqueousstream 103. In another embodiment, water is routed to a reverse osmosismembrane separation capable of separating monovalent and divalent metalcations from water to produce the treated aqueous stream 103. In anotherembodiment, water is routed to an ion exchange resin to generate thetreated aqueous stream 103 with acceptably low concentration of metalcations. In yet another embodiment, water can be routed to a commercialwater softening apparatus to generate the treated aqueous stream 103with an acceptably low concentration of divalent and multivalent metalcations. It is understood that any combinations of these water treatmentoptions may be employed to achieve the required treated watercharacteristics.

The treated aqueous stream 103 may be routed to any location in theprocess where it is needed. In one embodiment, a portion of stream 103is routed to a primary solid liquid separation zone 500 to serve as acloth wash and/or a wash for solids contained in the primary solidliquid separation zone 500.

In one embodiment, at least a portion of the treated aqueous stream 103is routed to heat exchanger zone 800. In another embodiment, at least aportion of treated aqueous stream 103 is routed to a fiber slurry zone200. In another embodiment, at least a portion of the treated aqueousstream 103 is routed to heat exchanger zone 800 and at least a portionof the treated aqueous stream 103 is routed to the fiber slurry zone200. One function of heat exchanger zone 800 is to generate a heatedaqueous stream 801 at a specific and controlled temperature.

In one embodiment, streams that can feed heat exchanger zone 800 are thetreated aqueous stream 103 and the second mother liquor stream 601. Inanother embodiment, streams that can feed heat exchanger zone 800comprise the treated aqueous stream 103, the primary recovered waterstream 703, the first mother liquor stream 501, and the second motherliquor stream 601.

Any equipment know in the art for controlling the temperature of stream801 may be used including, but not limited to, any heat exchanger withsteam used to provide a portion of the required energy, any heatexchanger with a heat transfer fluid used to provide a portion of therequired energy, any heat exchanger with electrical heating elementsused to provide a portion of the required energy, and any vessel or tankwith direct steam injection wherein the steam condenses and thecondensate mixes with the water feeds to heat exchanger zone 800.

The multicomponent fiber stream 90 is routed to fiber cutting zone 100to generate cut multicomponent fiber stream 101. The multicomponentfiber can be of any multicomponent structure known in the art. Themulticomponent fiber comprises a water dispersible sulfopolyester and awater non-dispersible polymer as previously discussed in thisdisclosure.

Any equipment know in the art may be used to cut multicomponent fiberstream 90 to generate cut multicomponent fiber stream 101. In oneembodiment, the length of the cut fibers in the cut multicomponent fiberstream 101 is less than about 50 mm. In other embodiments, the length ofcut fibers in the cut multicomponent fiber stream 101 is less than about25 mm, less than about 20 mm, less than about 15 mm, less than about 10mm, less than about 5 mm, or less than 2.5 mm.

The cut multicomponent fiber stream 101 and a portion of the treatedaqueous stream 103 are routed to a fiber slurry zone 200 to generate acut multicomponent fiber slurry 201 comprising water and cutmulticomponent fibers. In one embodiment, the weight % of cutmulticomponent fibers in the cut multicomponent fiber slurry 201 canrange from about 35 weight % to about 1% weight %, from about 25 weight% to about 1 weight %, from about 15 weight % to about 1 weight %, orfrom about 7 weight % to about 1 weight %.

The temperature of the cut multicomponent fiber slurry 201 can rangefrom about 5 degrees centigrade to about 45 degrees centigrade, fromabout 10 degrees centigrade to about 35 degrees centigrade, or fromabout 10 degrees centigrade to about 25 degrees centigrade. In oneembodiment, fiber slurry zone 200 comprises a tank with sufficientagitation to generate a suspension of cut multicomponent fiber in acontinuous aqueous phase.

Any equipment known in the art suitable for mixing a solid with waterand maintaining the resulting suspension of cut multicomponent fibers inthe continuous phase may be used in the fiber slurry zone 200. The fiberslurry zone 200 can comprise batch or continuous mixing devices operatedin continuous or batch mode. Suitable devices for use in the fiberslurry zone 200 include, but are not limited to, a hydro-pulper, acontinuous stirred tank reactor, a tank with agitation operated in batchmode.

The cut multicomponent fiber slurry 201 and a heated aqueous stream 801are routed to a mix zone 300 and combined to generate a heatedmulticomponent fiber slurry 301. The temperature of the heatedmulticomponent fiber slurry 301 influences the separation of the waterdispersible sulfopolyester portion of the cut multicomponent fiber fromthe water non-dispersible polymer portion of the cut multicomponentfiber in fiber opening zone 400. In other embodiments of the invention,the temperature of the heated multicomponent fiber slurry 301 can rangefrom about 55 degrees centigrade to about 100 degrees centigrade, fromabout 60 degrees centigrade to about 90 degrees centigrade, or fromabout 65 degrees centigrade to about 80 degrees centigrade.

The weight % of cut multicomponent fiber in the heated multicomponentfiber slurry 301 can be controlled. In other embodiments, the weight %of cut multicomponent fibers in the heated multicomponent fiber slurry301 can range from about 10 weight % to about 0.1% weight %, from about5 weight % to about 0.2 weight %, from about 3 weight % to about 0.3weight %, or from about 2 weight % to about 0.4 weight %.

Any device known in the art capable of mixing the heated aqueous stream801 with the cut multicomponent fiber slurry 201 may be used in mix zone300. Suitable devices include both continuous and batch mixing devices.In one embodiment, a suitable mixing device for mix zone 300 comprises atank and an agitator. In another embodiment, a suitable mixing devicecomprises a pipe or conduit.

In other embodiments, a suitable mixing device in mix zone 300 comprisesa pipe or conduit with a diameter such that the speed in the conduit issufficient to mix the cut multicomponent fiber slurry 201 and the heatedaqueous stream 801 wherein less than about 2 weight %, less than about 1weight %, or less than about 0.5 weight of cut multicomponent massentering the conduit per minute settles out and accumulates in theconduit.

The heated multicomponent fiber slurry 301 can then be routed to a fiberopening zone 400. One function of fiber opening zone 400 is to separatethe water dispersible polymer from the cut multicomponent fiber suchthat at least a portion of the water non-dispersible polymer microfibersseparate from the cut multicomponent fiber and become suspended in theopened microfiber slurry 401. In another embodiment of the invention,from about 50 weight % to about 100 weight % of water non-dispersiblepolymer microfiber contained in the cut multicomponent fiber slurry 201becomes suspended in the opened microfiber slurry 401 as waternon-dispersible polymer microfibers and is no longer a part of the cutmulticomponent fiber. In other embodiments, from about 75 weight % toabout 100 weight %, from about 90 weight % to about 100 weight %, orfrom about 95 weight % to about 100 weight % of the waternon-dispersible polymer microfiber contained in the cut multicomponentfiber stream 201 becomes suspended in the opened microfiber slurry 401as water non-dispersible polymer microfibers and are no longer a part ofa cut multicomponent fiber.

The diameter or denier of the starting cut multicomponent fiber instream 201 impacts the extent of separation of the water dispersiblesulfopolyester from the cut multicomponent fiber in the fiber openingzone 400. Typical multicomponent fiber types generally have a diameterin the range from about 12 microns to about 20 microns. Usefulmulticomponent fibers can have larger starting diameters to a size ofabout 40 microns diameter or more. The time required to separate adesired amount of water dispersible sulfopolyester from the cutmulticomponent fiber increases as the diameter of the cut multicomponentfiber in stream 201 increases.

Residence time, temperature, and shear forces in the fiber opening zone400 also influence the extent of separation of the water dispersiblesulfopolyester from the cut multicomponent fiber. The conditionsinfluencing the opening process in fiber opening zone 400 compriseresidence time, slurry temperature, and shear forces where the ranges ofwater temperature, residence time in the fiber opening zone 400, andamount of applied shear are dictated by the need to separate the waterdispersible sulfopolyester from the starting multicomponent fiber to asufficient degree to result in water non-dispersible polymer microfibersbecoming separated and suspended in the continuous aqueous phase of theopened microfiber slurry 401.

Residence time, temperature, and shear forces in fiber opening zone 400influence the extent of separation of the water dispersiblesulfopolyester from the cut multicomponent fiber. The temperature of thefiber opening zone 400 can range from about 55 degrees centigrade toabout 100 degrees centigrade, from about 60 degrees centigrade to about90 degrees centigrade, or from about 65 degrees centigrade to about 80degrees centigrade. The residence time in the fiber opening zone 400 canrange from about 5 minutes to about 10 seconds, from about 3 minutes toabout 20 seconds, or from about 2 minutes to about 30 seconds.Sufficient mixing is maintained in fiber opening zone 400 to maintain asuspension of cut water non-dispersible polymer microfibers such thatthe settling of the cut microfibers is minimal. In other embodiments ofthe invention, the mass per unit time of cut water non-dispersiblemicrofibers settling in the fiber opening zone 400 is less than about 5%of the mass per unit time of cut water non-dispersible polymermicrofibers entering the zone 400, less than about 3% of the mass perunit time of cut water non-dispersible polymer microfibers entering zone400, or less than about 1% of the mass per unit time of cut waternon-dispersible polymer microfibers entering the fiber opening zone 400.

Fiber opening in fiber opening zone 400 may be accomplished in anyequipment capable of allowing for acceptable ranges of residence time,temperature, and mixing. Examples of suitable equipment include, but arenot limited to, an agitated batch tank, a continuous stirred tankreactor, as shown in FIGS. 6 b and 6 c, and a pipe with sufficient flowto minimize solids from settling out of the slurry as shown in FIG. 6 a.One example of a unit operation to accomplish fiber opening in fiberopening zone 400 is a plug flow reactor where the heated multicomponentfiber slurry 301 is routed to zone 400 plug flow device, typically acircular pipe or conduit. The residence time of material in a plug flowdevice is calculated by dividing the filled volume within the device bythe volumetric flow rate in the device. Velocity of the mass in thedevice is defined by the cross sectional area of the flow channeldivided by the volumetric flow of the liquid through the device.

In other embodiments of the invention, the fiber opening zone 400 cancomprise a pipe or conduit wherein the velocity of mass flowing in thepipe can range from 0.1 ft/second to about 20 feet/second, from 0.2ft/sec to about 10 ft/sec, or from about 0.5 ft/sec to about 5 ft/sec.For flow of a fluid or slurry in a pipe or conduit, the Reynolds numberRe is a dimensionless number useful for describing the turbulence ormotion of fluid eddy currents that are irregular with respect both todirection and time. For flow in a pipe or tube, the Reynolds number isgenerally defined as:

${Re} = {\frac{\rho \; {vD}_{H}}{\mu} = {\frac{{vD}_{H}}{\nu} = \frac{{QD}_{H}}{\; {\nu \; A}}}}$

Where:

-   -   D_(H) is the hydraulic diameter of the pipe; L, (m).    -   Q is the volumetric flow rate (m³/s).    -   A is the pipe cross-sectional area (m²).    -   v is the mean velocity of the object relative to the fluid (SI        units: m/s).    -   μ is the dynamic viscosity of the fluid (Pa·s or N·s/m² or        kg/(m·s)).    -   v is the kinematic viscosity (v=μ/ρ) (m²/s).    -   ρ is the density of the fluid (kg/m³).        For flow in a pipe of diameter D, experimental observations show        that for fully developed flow, laminar flow occurs when        Re_(D)<2000, and turbulent flow occurs when Re_(D)>4000. In the        interval between 2300 and 4000, laminar and turbulent flows are        possible (‘transition’ flows), depending on other factors, such        as, pipe roughness and flow uniformity.

Fiber opening zone 400 can comprise a pipe or conduit to facilitate theopening process, and the Reynolds number for flow through the pipe orconduit in fiber opening zone 400 can range from about 2,100 to about6,000, from about 3,000 to about 6,000, or from about 3,500 to about6,000. In other embodiments, the fiber opening zone 400 can comprise apipe or conduit to facilitate the opening process, and the Reynoldsnumber for flow through the pipe or conduit is at least 2,500, at leastabout 3,500, or at least about 4,000.

Fiber opening zone 400 can be achieved in a pipe or conduit containing amixing device inserted within the pipe or conduit. The device cancomprise an in-line mixing device. The in-line mixing device can be astatic mixer with no moving parts. In another embodiment, the in-linemixing device comprises moving parts. Without being limiting, such anelement is a mechanical device for the purpose of imparting more mixingenergy to the heated multicomponent fiber slurry 301 than achieved bythe flow through the pipe. The device can be inserted at the beginningof the pipe section used as the fiber opening zone, at the end of thepipe section, or at any location within the pipe flow path.

The opened fiber slurry stream 401 comprising water non-dispersiblepolymer microfiber, water, and water dispersible sulfopolyester can berouted to a primary solid liquid separation zone 500 to generate amicrofiber product stream 503 comprising microfiber and a first motherliquor stream 501. In one embodiment, the first mother liquor stream 501comprises water and water dispersible sulfopolyester.

The weight % of solids in the opened microfiber slurry 401 can rangefrom about 0.1 weight % to about 20 weight %, from about 0.3 weight % toabout 10 weight %, from about 0.3 weight % to about 5 weight %, or fromabout 0.3 weight % to about 2.5 weight %.

The weight % of solids in the microfiber product stream 503 can rangefrom about 10 weight % to about 65 weight %, from about 15 weight % toabout 50 weight %, from about 25 weight % to about 45 weight %, or fromabout 30 weight % to about 40 weight %.

Separation of the microfiber product stream 503 from the openedmicrofiber slurry 401 can be accomplished by any method known in theart. In one embodiment, wash stream 103 comprising water is routed tothe primary solid liquid separation zone 500. Wash stream 103 can beused to wash the microfiber product stream in the primary solid liquidseparation zone 500 and/or the filter cloth media in the primary solidliquid separation zone 500 to generate wash liquor stream 502. A portionup to 100 weight % of wash liquor stream 502 can be combined with theopened microfiber slurry 401 prior to entering the primary solid liquidseparation zone 500. Wash liquor stream 502 can contain microfiber. Inone embodiment, the grams of microfiber mass breaking though the filtermedia with openings up to 2000 microns in the primary solid liquidseparation zone 500 ranges from about 1 to 2 grams/cm² of filter area.In other embodiments of the invention, the filter openings in the filtermedia in the primary solid liquid separation zone 500 can range fromabout 43 microns to 3000 microns, from about 100 microns to 2000microns, or from about 500 microns to about 2000 microns.

Separation of the microfiber product stream from the opened microfiberslurry in primary solid liquid separation zone 500 may be accomplishedby a single or multiple solid liquid separation devices. Separation inthe primary solid liquid separation zone 500 may be accomplished by asolid liquid separation device or devices operated in batch and orcontinuous fashion. Suitable solid liquid separation devices in theprimary solid liquid separation zone 500 can include, but is not limitedto, at least one of the following: perforated basket centrifuges,continuous vacuum belt filters, batch vacuum nutschfilters, batchperforated settling tanks, twin wire dewatering devices, continuoushorizontal belt filters with a compressive zone, non vibrating inclinedscreen devices with wedge wire filter media, continuous vacuum drumfilters, dewatering conveyor belts, and the like.

In one embodiment, the primary solid liquid separation zone 500comprises a twin wire dewatering device wherein the opened microfibersturry 401 is routed to a tapering gap between a pair of travelingfilter cloths traveling in the same direction. In the first zone of thetwin wire dewatering device, water drains from the opened microfiberslurry 401 due to gravity and the every narrowing gap between the twomoving filter cloths. In a downstream zone of the twin wire dewateringdevice, the two filter cloths and the microfiber mass between the twofilter cloths are compressed one or more times to mechanically reducemoisture in the microfiber mass. In one embodiment, mechanicaldewatering is accomplished by passing the two filter cloths andcontained microfiber mass through at least one set of rollers that exerta compressive force on the two filter cloths and microfiber massbetween. In another embodiment, mechanical dewatering is accomplished bypassing the two filter cloths and microfiber mass between at least onepressure roller and a fixed surface.

In other embodiments of the invention, the force exerted by mechanicaldewatering can range from about 25 to about 300 lbs/linear inch offilter media width, from about 50 to about 200 lbs/linear inch of filtermedia width, or from about 70 to about 125 lbs/linear inch of filtermedia width. The microfiber product stream 503 is discharged from thetwin wire water dewatering device as the two filter cloths separate anddiverge at the solids discharge zone of the device. The thickness of thedischarged microfiber mass can range from about 0.2 inches to about 1.5inches, from about 0.3 inches to about 1.25 inches, or from about 0.4inches to about 1 inch. In one embodiment, a wash stream comprisingwater is continuously applied to the filter media. In anotherembodiment, a wash stream comprising water is periodically applied tothe filter media.

In another embodiment, the primary solid liquid separation zone 500comprises a belt filter device comprising a gravity drainage zone and apressure dewatering zone as illustrated in FIG. 7. Opened microfiberslurry 401 is routed to a tapering gap between a pair of moving filtercloths traveling in the same direction which first pass through agravity drainage zone and then pass through a pressure dewatering zoneor press zone comprising a convoluted arrangement of rollers asillustrated in FIG. 6 b. As the belts are fed through the rollers, wateris squeezed out of the solids. When the belts pass through the finalpair of rollers in the process, the filter cloths are separated and thesolids exit the belt filter device.

In another embodiment of the invention, at least a portion of the watercontained in the first mother liquor stream 501 comprising water andwater dispersible sulfopolyester polymer is recovered and recycled. Thefirst mother liquor stream 501 can be recycled to the primary solidliquid separation zone 500. Depending on the efficiency of the primaryliquid separation zone in the removal of the water non-dispersiblemicrofiber, the first mother liquid stream 501 can be recycled to thefiber slurry zone 200, the mix zone 300, the fiber opening zone 400, orthe heat exchanger zone 800 prior to being routed to Zones 200, 300and/or 400. The first mother liquor stream 501 can contain a smallamount of solids comprising water non-dispersible polymer microfiber dueto breakthrough and cloth wash. In one embodiment, the grams of waternon-dispersible polymer microfiber mass breaking though filter media inthe primary solid liquid separation zone with openings up to 2000microns ranges from about 1 to about 2 grams/cm² of filter area. It isdesirable to minimize the water non-dispersible polymer microfibersolids in the first mother liquor stream 501 prior to routing stream 501to the primary concentration zone 700 and heat exchange zone 800 wherewater non-dispersible polymer microfiber solids can collect andaccumulate in the zones having a negative impact on their function.

A secondary solid liquid separation zone 600 can serve to remove atleast a portion of water non-dispersible polymer microfiber solidspresent in the first mother liquor stream 501 to generate a secondarywet cake stream 602 comprising water non-dispersible microfiber and asecond mother liquor stream 601 comprising water and water dispersiblesulfopolyester.

In one embodiment, the second mother liquor stream 601 can be routed toa primary concentration zone 700 and or heat exchanger zone 800 whereinthe weight % of the second mother liquor stream 601 routed to theprimary concentration zone 700 can range from 0% to 100% with thebalance of the stream being routed to heat exchanger zone 800. Thesecond mother liquor stream 601 can be recycled to the fiber slurry zone200, the mix zone 300, the fiber opening zone 400, or the heat exchangerzone 800 prior to being routed to Zones 200, 300 and/or 400. The amountof the water dispersible sulfopolyester in the second mother liquorstream routed to the fiber opening zone 400 can range from about 0.01weight % to about 7 weight %, based on the weight % of the second motherliquor stream, or from about 0.1 weight % to about 7 weight %, fromabout 0.2 weight % to about 5 weight %, or from about 0.3 weight % toabout 3 weight %.

Any portion of the second mother liquor 601 routed to primaryconcentration zone is subjected to a separation process to generate aprimary recovered water stream 703 and a primary polymer concentratestream 702 enriched in water dispersible sulfopolyester wherein theweight % of water dispersible sulfopolyester in the primary polymerconcentrate stream 702 can range from about 5 weight % to about 85%,from about 10 weight % to about 65 weight %, or from about 15 weight %to about 45 weight %. The primary recovered water stream 703 can berecycled to the fiber slurry zone 200, the mix zone 300, the fiberopening zone 400, or the heat exchanger zone 800 prior to being routedto Zones 200, 300 and/or 400. The amount of the water dispersiblesulfopolyester in the second mother liquor stream routed to the fiberopening zone 400 can range from about 0.01 weight % to about 7 weight %,based on the weight % of the second mother liquor stream, or from about0.1 weight % to about 7 weight %, from about 0.2 weight % to about 5weight %, or from about 0.3 weight % to about 3 weight %.

Water can be removed from the second mother liquor stream 601 by anymethod know in the art in the primary concentration zone 700 to producethe primary polymer concentrate stream 702. In one embodiment, removalof water involves an evaporative process by boiling water away in batchor continuous evaporative equipment. For example, at least one thin filmevaporator can be used for this application. In another embodiment,membrane technology comprising nanofiltration media can be used togenerate the primary polymer concentrate stream 702. In anotherembodiment, a process comprising extraction equipment may be used toextract water dispersible polymer from the second mother liquor stream601 and generate the primary polymer concentrate stream 702. It isunderstood than any combination of evaporation, membrane, and extractionsteps may be used to separate the water dispersible sulfopolyester fromthe second mother liquor stream 601 and generate the primary polymerconcentrate stream 702. The primary polymer concentration stream 702 maythen exit the process.

In one embodiment, the primary polymer concentrate stream 702 can berouted to a secondary concentration zone 900 to generate a meltedpolymer stream 903 comprising water dispersible sulfopolyester whereinthe weight % of polymer ranges from about 95% to about 100% and a vaporstream 902 comprising water. In one embodiment, the 903 comprises waterdispersible sulfopolyester. Equipment suitable for the secondaryconcentration zone 900 includes any equipment known in the art capableof being fed an aqueous dispersion of water dispersible polymer andgenerating a 95% to 100% water dispersible polymer stream 903. Thisembodiment comprises feeding an aqueous dispersion of water dispersiblesulfopolyester polymer to a secondary concentration zone 902. Thetemperature of feed stream is typically below 100° C.

In one embodiment, the secondary concentration zone 900 comprises atleast one device characterized by a jacketed tubular shell containing arotating convey screw wherein the convey screw is heated with a heattransfer fluid or steam and comprises both convey and high shear mixingelements. The jacket or shell is vented to allow for vapor to escape.The shell jacket may be zoned to allow for different temperature setpoints along the length of the device. During continuous operation, theprimary polymer concentrate stream 702 comprises water and waterdispersible sulfopolyester and is continuously fed to the secondaryconcentration zone 900. Within the device, during steady state, massexists in at least three distinct and different forms. Mass first existsin the device as an aqueous dispersion of water dispersiblesulfopolyester polymer. As the aqueous dispersion of sulfopolyesterpolymer moves through the device, water is evaporated due to the heat ofthe jacket and internal screw. When sufficient water is evaporated, themass becomes a second form comprising a viscous plug at a temperatureless than the melt temperature of the sulfopolyester polymer. Theaqueous dispersion cannot flow past this viscous plug and is confined tothe first aqueous dispersion zone of the device. Due to the heat of thejacket, heat of the internally heated screw, and the heat due to mixingshear forces of this high viscosity plug mass, substantially all thewater present at this location evaporates, and the temperature risesuntil the melt temperature of the sulfopolyester is reached resulting inthe third and final physical form of mass in the device comprisingmelted sulfopolyester polymer. The melted sulfopolyester polymer thenexits the device through an extrusion dye and is typically cooled andcut into pellets by any fashion know in the art. It is understood thatthe device for secondary concentration zone 900 described above may alsobe operated in batch fashion wherein the three physical forms of massdescribed above occur throughout the length of the device but atdifferent times in sequential order beginning with the aqueousdispersion, the viscous plug mass, and finally the sulfopolyester melt.

In one embodiment, vapor generated in the secondary concentration zone900 may be condensed and routed to heat exchanger zone 800, discarded,and/or routed to wash stream 103. In another embodiment, condensed vaporstream 902 comprising water vapor can be routed to heat exchanger zone800 to provide at least part of the energy required for generating therequired temperature for stream 801. The melted polymer stream 903comprising water dispersible polymer comprising sulfopolyester in themelt phase can be cooled and chopped into pellets by any method known inthe art.

Impurities can enter the process and concentrated in water recovered andrecycled. One or more purge streams (603 and 701) can be utilized tocontrol the concentration of impurities in the second mother liquor 601and primary recovered water stream 701 to acceptable levels. In oneembodiment, a portion of the second mother liquor stream 601 can beisolated and purged from the process. In one embodiment, a portion ofthe primary recovered water stream 701 can be isolated and purged fromthe process.

The invention is further illustrated by the following examples.

EXAMPLES

All pellet samples were predried under vacuum at room temperature for atleast 12 hours. The dispersion times shown in Table 3 are for eithercomplete dispersion or dissolution of the nonwoven fabric samples. Theabbreviation “CE”, used in Tables 2 and 3 mean “comparative example”.

Example 1

A sulfopolyester containing 76 mole %, isophthalic acid, 24 mole % ofsodiosulfoisophthalic acid, 76 mole % diethylene glycol, and 24 mole %1,4-cyclohexanedimethanol with an Ih.V. of 0.29 and a Tg of 48° C. wasmeltblown through a nominal 6-inch die (30 holes/inch in the nosepiece)onto a cylindrical collector using the conditions shown in Table 1.Interleafing paper was not required. A soft, handleable, flexible webwas obtained that did not block during the roll winding operation.Physical properties are provided in Table 2. A small piece (1″×3″) ofthe nonwoven fabric was easily dispersed in both room temperature (RT)and 50° C. water with slight agitation as shown by data in Table 3.

TABLE 1 Melt Blowing Conditions Operating Condition Typical Value DieConfiguration Die tip hole diameter 0.0185 inches Number of holes 120Air gap 0.060 inches Set back 0.060 inches Extruder Barrel Temperatures(° F.) Zone 1 350 Zone 2 510 Zone 3 510 Die Temperatures (° F.) Zone 4510 Zone 5 510 Zone 6 510 Zone 7 510 Zone 8 510 Air Temperatures (° F.)Furnace exit 1 350 Furnace exit 2 700 Furnace exit 3 700 Die 530-546Extrusion Conditions Air pressure 3.0 psi Melt pressure after pump99-113 psi Take Up Conditions Throughput 0.3 g/hole/min 0.5 g/hole/minBasis weight 36 g/m² Collector speed 20 ft/min Collector distance 12inches

TABLE 2 Physical Properties of Nonwovens IhV Filament Diameter (μm)(before/ Tg/Tm (° C.) Example Minimum Maximum Average after)(sulfopoly./PP) 1 5 18 8.7 0.29/0.26 39/not applicable 2 3 11 7.70.40/0.34 36/not applicable CE 1 2 20 8 Not 36/163 measured CE 2 4 10 7Not 36/164 measured CE 3 4 11 6 Not 35/161 measured

TABLE 3 Dispersability of Nonwovens Water Initial Significant CompleteTemperature Disintegration Disintegration Dispersion Example (° C.)(minutes) (minutes) (minutes) 1 23 <0.25 1 2 50 <0.17 0.5 1 2 23 8 14 1950 <0.5 5 8 80 <0.5 2 5 CE 1 23 0.5 >15 No dispersion of PP 50 0.5 >15No dispersion of PP CE 2 23 0.5 >15 No dispersion of PP 50 0.5 >15 Nodispersion of PP CE 3 23 <0.5 6 No dispersion of PP 50 <0.5 4 Nodispersion of PP

Example 2

A sulfopolyester containing 89 mole %, isophthalic acid, 11 mole % ofsodiosulfoisophthalic acid, 72 mole % diethylene glycol, and 28 moleethylene glycol with an Ih.V. of 0.4 and a Tg of 35° C. was meltblownthrough a 6-inch die using conditions similar to those in Table 1. Asoft, handleable, flexible web was obtained that did not block during aroll winding operation. Physical properties are provided in Table 2. Asmall piece (1″×2″) of the nonwoven fabric was easily and completelydispersed at 50° C. and 80° C.; at RT (23° C.), the fabric required alonger period of time for complete dispersion as shown by the data inTable 3.

It was found that the compositions in Examples 1 and 2 can be overblownonto other nonwoven substrates. It is also possible to condense and wrapshaped or contoured forms that are used instead of conventional webcollectors. Thus, it is possible to obtain circular “roving” or plugforms of the webs.

Comparative Examples 1-3

Pellets of a sulfopolyester containing 89 mole %, isophthalic acid, 11mole % of sodiosulfoisophthalic acid, 72 mole % diethylene glycol, and28 mole % ethylene glycol with an Ih.V. of 0.4 and a Tg of 35° C. werecombined with polypropylene (BaseII PF 008) pellets in bicomponentratios (by weight %) of:

75 PP: 25 sulfopolyester (Example 3)

50 PP: 50 sulfopolyester (Example 4)

25 PP: 75 sulfopolyester (Example 5)

The PP had a MFR (melt flow rate) of 800. A melt blowing operation wasperformed on a line equipped with a 24-inch wide die to yieldhandleable, soft, flexible, but nonblocking webs with the physicalproperties provided in Table 2. Small pieces (1″×4″) of nonwoven fabricreadily disintegrated as reported in Table 3. None of the fibers,however, were completely water-dispersible because of the insolublepolypropylene component.

Example 3

A circular piece (4″ diameter) of the nonwoven produced in Example 2 wasused as an adhesive layer between two sheets of cotton fabric. AHannifin melt press was used to fuse the two sheets of cotton togetherby applying a pressure 35 psig at 200° C. for 30 seconds. The resultantassembly exhibited exceptionally strong bond strength. The cottonsubstrate shredded before adhesive or bond failure. Similar results havealso been obtained with other cellulosics and with PET polyestersubstrates. Strong bonds were also produced by ultrasonic bondingtechniques.

Comparative Example 4

A PP (Exxon 3356G) with a 1200 MFR was melt blown using a 24″ die toyield a flexible nonwoven fabric that did not block and was easilyunwound from a roll. Small pieces (1″×4″) did not show any response(i.e., no disintegration or loss in basis weight) to water when immersedin water at RT or 50° C. for 15 minutes.

Example 4

Unicomponent fibers of a sulfopolyester containing 82 mole % isophthalicacid, 18 mole % of sodiosulfoisophthalic acid, 54 mole % diethyleneglycol, and 46 mole % 1,4-cyclohexanedimethanol with a Tg of 55° C. weremelt spun at melt temperatures of 245° C. (473° F.) on a lab staplespinning line. As-spun denier was approximately 8 d/f. Some blocking wasencountered on the take-up tubes, but the 10-filament strand readilydissolved within 10-19 seconds in unagitated, demineralized water at 82°C. and a pH between 5 and 6.

Example 5

Unicomponent fibers obtained from a blend (75:25) of a sulfopolyestercontaining 82 mole % isophthalic acid, 18 mole % ofsodiosulfoisophthalic acid, 54 mole % diethylene glycol, and 46 mole %1,4-cyclohexanedimethanol (Tg of 55° C.) and a sulfopolyester containing91 mole % isophthalic acid, 9 mole % of sodiosulfoisophthalic acid, 25mole % diethylene glycol, and 75 mole % 1,4-cyclohexanedimethanol (Tg of65° C.), respectively, were melt spun on a lab staple spinning line. Theblend has a Tg of 57° C. as calculated by taking a weighted average ofthe Tg's of the component sulfopolyesters. The 10-filament strands didnot show any blocking on the take-up tubes, but readily dissolved within20-43 seconds in unagitated, demineralized water at 82° C. and a pHbetween 5 and 6.

Example 6

The blend described in Example 5 was co-spun with PET to yieldbicomponent islands-in-the-sea fibers. A configuration was obtainedwhere the sulfopolyester “sea” is 20 weight % of the fiber containing 80weight % of PET “islands”. The spun yarn elongation was 190% immediatelyafter spinning. Blocking was not encountered as the yarn wassatisfactorily unwound from the bobbins and processed a week afterspinning. In a subsequent operation, the “sea” was dissolved by passingthe yarn through an 88° C. soft water bath leaving only fine PETfilaments.

Example 7

This prophetic example illustrates the possible application of themulticomponent and microdenier fibers of the present invention to thepreparation of specialty papers. The blend described in Example 5 isco-spun with PET to yield bicomponent islands-in-the-sea fibers. Thefiber contains approximately 35 weight % sulfopolyester “sea” componentand approximately 65 weight % of PET “islands”. The uncrimped fiber iscut to ⅛ inch lengths. In simulated papermaking, these short-cutbicomponent fibers are added to the refining operation. Thesulfopolyester “sea” is removed in the agitated, aqueous slurry therebyreleasing the microdenier PET fibers into the mix. At comparableweights, the microdenier PET fibers (“islands”) are more effective toincrease paper tensile strength than the addition of coarse PET fibers.

Comparative Example 8

Bicomponent fibers were made having a 108 islands in the sea structureon a spunbond line using a 24″ wide bicomponent spinneret die from HillsInc., Melbourne, Fla., having a total of 2222 die holes in the dieplate. Two extruders were connected to melt pumps which were in turnconnected to the inlets for both components in the fiber spin die. Theprimary extruder (A) was connected to the inlet which metered a flow ofEastman F61HC PET polyester to form the island domains in the islands inthe sea fiber cross-section structure. The extrusion zones were set tomelt the PET entering the die at a temperature of 285° C. The secondaryextruder (B) processed Eastman AQ 55S sulfopolyester polymer fromEastman Chemical Company, Kingsport, Tenn. having an inherent viscosityof about 0.35 and a melt viscosity of about 15,000 poise, measured at240° C. and 1 rad/sec sheer rate and 9,700 poise measured at 240° C. and100 rad/sec sheer rate in a Rheometric Dynamic Analyzer RDAII(Rheometrics Inc. Piscataway, N.J.) rheometer. Prior to performing amelt viscosity measurement, the sample was dried for two days in avacuum oven at 60° C. The viscosity test was performed using a 25 mmdiameter parallel-plate geometry at 1 mm gap setting. A dynamicfrequency sweep was run at a strain rate range of 1 to 400 rad/sec and10% strain amplitude. Then, the viscosity was measured at 240° C. andstrain rate of 1 rad/sec. This procedure was followed in determining theviscosity of the sulfopolyester materials used in the subsequentexamples. The secondary extruder was set to melt and feed the AQ 55Spolymer at a melt temperature of 255° C. to the spinnerette die. The twopolymers were formed into bicomponent extrudates by extrusion at athroughput rate of 0.6 g/hole/min. The volume ratio of PET to AQ 55S inthe bicomponent extrudates was adjusted to yield 60/40 and 70/30 ratios.

An aspirator device was used to melt draw the bicomponent extrudates toproduce the bicomponent fibers. The flow of air through the aspiratorchamber pulled the resultant fibers down. The amount of air flowingdownward through the aspirator assembly was controlled by the pressureof the air entering the aspirator. In this example, the maximum pressureof the air used in the aspirator to melt draw the bicomponent extrudateswas 25 psi. Above this value, the airflow through the aspirator causedthe extrudates to break during this melt draw spinning process as themelt draw rate imposed on the bicomponent extrudates was greater thanthe inherent ductility of the bicomponent extrudates. The bicomponentfibers were laid down into a non-woven web having a fabric weight of 95grams per square meter (gsm). Evaluation of the bicomponent fibers inthis nonwoven web by optical microscopy showed that the PET was presentas islands in the center of the fiber structure, but the PET islandsaround the outer periphery of the bicomponent fiber nearly coalescedtogether to form a nearly continuous ring of PET polymer around thecircumference of the fibers which is not desirable. Microscopy foundthat the diameter of the bicomponent fibers in the nonwoven web wasgenerally between 15-19 microns, corresponding to an average fiberas-spun denier of about 2.5 denier per filament (dpf). This represents amelt drawn fiber speed of about 2160 meters per minute. As-spun denieris defined as the denier of the fiber (weight in grams of 9000 meterslength of fiber) obtained by the melt extrusion and melt drawing steps.The variation in bicomponent fiber diameter indicated non-uniformity inspun-drawing of the fibers.

The non-woven web samples were conditioned in a forced-air oven for fiveminutes at 120° C. The heat treated web exhibited significant shrinkagewith the area of the nonwoven web being decreased to only about 12% ofthe initial area of the web before heating. Although not intending to bebound by theory, due to the high molecular weight and melt viscosity ofthe AQ 55S sulfopolyester used in the fiber, the bicomponent extrudatescould not be melt drawn to the degree required to cause strain inducedcrystallization of the PET segments in the fibers. Overall, the AQ 55Ssulfopolyester having this specific inherent viscosity and meltviscosity was not acceptable as the bicomponent extrudates could not beuniformly melt drawn to the desired fine denier.

Example 8

A sulfopolyester polymer with the same chemical composition ascommercial Eastman AQ55S polymer was produced, however, the molecularweight was controlled to a lower value characterized by an inherentviscosity of about 0.25. The melt viscosity of this polymer was 3300poise measured at 240° C. and 1 rad/sec shear rate.

Example 9

Bicomponent extrudates having a 16-segment segmented pie structure weremade using a bicomponent spinneret die from Hills Inc., Melbourne, Fla.,having a total of 2222 die holes in the 24 inch wide die plate on aspunbond equipment. Two extruders were used to melt and feed twopolymers to this spinnerette die. The primary extruder (A) was connectedto the inlet which fed Eastman F61HC PET polyester melt to form thedomains or segment slices in the segmented pie cross-section structure.The extrusion zones were set to melt the PET entering the spinnerettedie at a temperature of 285° C. The secondary extruder (B) melted andfed the sulfopolyester polymer of Example 8. The secondary extruder wasset to extrude the sulfopolyester polymer at a melt temperature of 255°C. into the spinnerette die. Except for the spinnerette die used andmelt viscosity of the sulfopolyester polymer, the procedure employed inthis example was the same as in Comparative Example 8. The meltthroughput per hole was 0.6 gm/min. The volume ratio of PET tosulfopolyester in the bicomponent extrudates was set at 70/30 whichrepresents a weight ratio of about 70/30.

The bicomponent extrudates were melt drawn using the same aspirator usedin Comparative Example 8 to produce the bicomponent fibers. Initially,the input air to the aspirator was set to 25 psi and the fibers hadas-spun denier of about 2.0 with the bicomponent fibers exhibiting auniform diameter profile of about 14-15 microns. The air to theaspirator was increased to a maximum available pressure of 45 psiwithout breaking the melt extrudates during melt drawing. Using 45 psiair, the bicomponent extrudates were melt drawn down to a fiber as-spundenier of about 1.2 with the bicomponent fibers exhibiting a diameter of11-12 microns when viewed under a microscope. The speed during the meltdraw process was calculated to be about 4500 m/min. Although notintending to be bound by theory, at melt draw rates approaching thisspeed, it is believed that strain induced crystallization of the PETduring the melt drawing process begins to occur. As noted above, it isdesirable to form some oriented crystallinity in the PET fiber segmentsduring the fiber melt draw process so that the nonwoven web will be moredimensionally stable during subsequent processing.

The bicomponent fibers using 45 psi aspirator air pressure were laiddown into a nonwoven web with a weight of 140 grams per square meter(gsm). The shrinkage of the nonwoven web was measured by conditioningthe material in a forced-air oven for five minutes at 120° C. Thisexample represents a significant reduction in shrinkage compared to thefibers and fabric of Comparative Example 8.

This nonwoven web having 140 gsm fabric weight was soaked for fiveminutes in a static deionized water bath at various temperatures. Thesoaked nonwoven web was dried, and the percent weight loss due tosoaking in deionized water at the various temperatures was measured asshown in Table 4.

TABLE 4 Soaking Temperature 25° C. 33° C. 40° C. 72° C. Nonwoven WebWeight 3.3 21.7 31.4 31.7 Loss (%)

The sulfopolyester dissipated very readily into deionized water at atemperature of about 25° C. Removal of the sulfopolyester from thebicomponent fibers in the nonwoven web is indicated by the % weightloss. Extensive or complete removal of the sulfopolyester from thebicomponent fibers were observed at temperatures at or above 33° C. Ifhydroentanglement is used to produce a nonwoven web of these bicomponentfibers comprising the present sulfopolyester polymer of Example 8, itwould be expected that the sulfopolyester polymer would be extensivelyor completely removed by the hydroentangling water jets if the watertemperature was above ambient. If it is desired that very littlesulfopolyester polymer be removed from these bicomponent fibers duringthe hydroentanglement step, low water temperature, less than about 25°C., should be used.

Example 10

A sulfopolyester polymer was prepared with the following diacid and diolcomposition: diacid composition (71 mole % terephthalic acid, 20 moleisophthalic acid, and 9 mole % 5-(sodiosulfo) isophthalic acid) and diolcomposition (60 mole % ethylene glycol and 40 mole % diethylene glycol).The sulfopolyester was prepared by high temperature polyesterificationunder vacuum. The esterification conditions were controlled to produce asulfopolyester having an inherent viscosity of about 0.31. The meltviscosity of this sulfopolyester was measured to be in the range ofabout 3000-4000 poise at 240° C. and 1 rad/sec shear rate.

Example 11

The sulfopolyester polymer of Example 10 was spun into bicomponentsegmented pie fibers and nonwoven web according to the same proceduredescribed in Example 9. The primary extruder (A) fed Eastman F61HC PETpolyester melt to form the larger segment slices in the segmented piestructure. The extrusion zones were set to melt the PET entering thespinnerette die at a temperature of 285° C. The secondary extruder (B)processed the sulfopolyester polymer of Example 10 which was fed at amelt temperature of 255° C. into the spinnerette die. The meltthroughput rate per hole was 0.6 gm/min. The volume ratio of PET tosulfopolyester in the bicomponent extrudates was set at 70/30 whichrepresents the weight ratio of about 70/30. The cross-section of thebicomponent extrudates had wedge shaped domains of PET withsulfopolyester polymer separating these domains.

The bicomponent extrudates were melt drawn using the same aspiratorassembly used in Comparative Example 8 to produce the bicomponent fiber.The maximum available pressure of the air to the aspirator withoutbreaking the bicomponent fibers during drawing was 45 psi. Using 45 psiair, the bicomponent extrudates were melt drawn down to bicomponentfibers with as-spun denier of about 1.2 with the bicomponent fibersexhibiting a diameter of about 11-12 microns when viewed under amicroscope. The speed during the melt drawing process was calculated tobe about 4500 m/min.

The bicomponent fibers were laid down into nonwoven webs having weightsof 140 gsm and 110 gsm. The shrinkage of the webs was measured byconditioning the material in a forced-air oven for five minutes at 120°C. The area of the nonwoven webs after shrinkage was about 29% of thewebs' starting areas.

Microscopic examination of the cross section of the melt drawn fibersand fibers taken from the nonwoven web displayed a very good segmentedpie structure where the individual segments were clearly defined andexhibited similar size and shape. The PET segments were completelyseparated from each other so that they would form eight separate PETmonocomponent fibers having a pie-slice shape after removal of thesulfopolyester from the bicomponent fiber.

The nonwoven web, having 110 gsm fabric weight, was soaked for eightminutes in a static deionized water bath at various temperatures. Thesoaked nonwoven web was dried and the percent weight loss due to soakingin deionized water at the various temperatures was measured as shown inTable 5.

TABLE 5 Soaking Temperature 36° C. 41° C. 46° C. 51° C. 56° C. 72° C.Nonwoven Web 1.1 2.2 14.4 25.9 28.5 30.5 Weight Loss (%)

The sulfopolyester polymer dissipated very readily into deionized waterat temperatures above about 46° C., with the removal of thesulfopolyester polymer from the fibers being very extensive or completeat temperatures above 51° C. as shown by the weight loss. A weight lossof about 30% represented complete removal of the sulfopolyester from thebicomponent fibers in the nonwoven web. If hydroentanglement is used toprocess this non-woven web of bicomponent fibers comprising thissulfopolyester, it would be expected that the polymer would not beextensively removed by the hydroentangling water jets at watertemperatures below 40° C.

Example 12

The nonwoven webs of Example 11 having basis weights of both 140 gsm and110 gsm were hydroentangled using a hydroentangling apparatusmanufactured by Fleissner, GmbH, Egelsbach, Germany. The machine hadfive total hydroentangling stations wherein three sets of jets contactedthe top side of the nonwoven web and two sets of jets contacted theopposite side of the nonwoven web. The water jets comprised a series offine orifices about 100 microns in diameter machined in two-feet widejet strips. The water pressure to the jets was set at 60 bar (Jet Strip#1), 190 bar (Jet Strips #2 and 3), and 230 bar (Jet Strips #4 and 5).During the hydroentanglement process, the temperature of the water tothe jets was found to be in the range of about 40-45° C. The nonwovenfabric exiting the hydroentangling unit was strongly tied together. Thecontinuous fibers were knotted together to produce a hydroentanglednonwoven fabric with high resistance to tearing when stretched in bothdirections.

Next, the hydroentangled nonwoven fabric was fastened onto a tenterframe comprising a rigid rectangular frame with a series of pins aroundthe periphery thereof. The fabric was fastened to the pins to restrainthe fabric from shrinking as it was heated. The frame with the fabricsample was placed in a forced-air oven for three minutes at 130° C. tocause the fabric to heat set while being restrained. After heat setting,the conditioned fabric was cut into a sample specimen of measured size,and the specimen was conditioned at 130° C. without restraint by atenter frame. The dimensions of the hydroentangled nonwoven fabric afterthis conditioning were measured and only minimal shrinkage (<0.5%reduction in dimension) was observed. It was apparent that heat settingof the hydroentangled nonwoven fabric was sufficient to produce adimensionally stable nonwoven fabric.

The hydroentangled nonwoven fabric, after being heat set as describedabove, was washed in 90° C. deionized water to remove the sulfopolyesterpolymer and leave the PET monocomponent fiber segments remaining in thehydroentangled fabric. After repeated washings, the dried fabricexhibited a weight loss of approximately 26%. Washing the nonwoven webbefore hydroentangling demonstrated a weight loss of 31.3%. Therefore,the hydroentangling process removed some of the sulfopolyester from thenonwoven web, but this amount was relatively small. In order to lessenthe amount of sulfopolyester removed during hydroentanglement, the watertemperature of the hydroentanglement jets should be lowered to below 40°C.

The sulfopolyester of Example 10 was found to give segmented pie fibershaving good segment distribution where the water non-dispersable polymersegments formed individual fibers of similar size and shape afterremoval of the sulfopolyester polymer. The rheology of thesulfopolyester was suitable to allow the bicomponent extrudates to bemelt drawn at high rates to achieve fine denier bicomponent fibers withas-spun denier as low as about 1.0. These bicomponent fibers are capableof being laid down into a non-woven web which could be hydroentangledwithout experiencing significant loss of sulfopolyester polymer toproduce the nonwoven fabric. The nonwoven fabric produced byhydroentangling the non-woven web exhibited high strength and could beheat set at temperatures of about 120° C. or higher to produce nonwovenfabric with excellent dimensional stability. The sulfopolyester polymerwas removed from the hydroentangled nonwoven fabric in a washing step.This resulted in a strong nonwoven fabric product with lighter fabricweight and much greater flexibility and softer hand. The monocomponentPET fibers in this nonwoven fabric product were wedge shaped andexhibited an average denier of about 0.1.

Example 13

A sulfopolyester polymer was prepared with the following diacid and diolcomposition: diacid composition (69 mole % terephthalic acid, 22.5 mole% isophthalic acid, and 8.5 mole % 5-(sodiosulfo)isophthalic acid) anddiol composition (65 mole % ethylene glycol and 35 mole % diethyleneglycol). The sulfopolyester was prepared by high temperaturepolyesterification under vacuum. The esterification conditions werecontrolled to produce a sulfopolyester having an inherent viscosity ofabout 0.33. The melt viscosity of this sulfopolyester was measured to bein the range of about 3000-4000 poise at 240° C. and 1 rad/sec shearrate.

Example 14

The sulfopolyester polymer of Example 13 was spun into bicomponentislands-in-sea cross-section configuration with 16 islands on a spunbondline. The primary extruder (A) fed Eastman F61HC PET polyester melt toform the islands in the islands-in-sea structure. The extrusion zoneswere set to melt the PET entering the spinnerette die at a temperatureof about 290° C. The secondary extruder (B) processed the sulfopolyesterpolymer of Example 13 which was fed at a melt temperature of about 260°C. into the spinnerette die. The volume ratio of PET to sulfopolyesterin the bicomponent extrudates was set at 70/30 which represents theweight ratio of about 70/30. The melt throughput rate through thespinneret was 0.6 g/hole/minute. The cross-section of the bicomponentextrudates had round shaped island domains of PET with sulfopolyesterpolymer separating these domains.

The bicomponent extrudates were melt drawn using an aspirator assembly.The maximum available pressure of the air to the aspirator withoutbreaking the bicomponent fibers during melt drawing was 50 psi. Using 50psi air, the bicomponent extrudates were melt drawn down to bicomponentfibers with as-spun denier of about 1.4 with the bicomponent fibersexhibiting a diameter of about 12 microns when viewed under amicroscope. The speed during the drawing process was calculated to beabout 3900 m/min.

Example 15

The sulfopolyester polymer of Example 13 was spun into bicomponentislands-in-the-sea cross-section fibers with 64 islands fibers using abicomponent extrusion line. The primary extruder fed Eastman F61HCpolyester melt to form the islands in the islands-in-the-sea fibercross-section structure. The secondary extruder fed the sulfopolyesterpolymer melt to form the sea in the islands-in-sea bicomponent fiber.The inherent viscosity of polyester was 0.61 dL/g while the meltviscosity of dry sulfopolyester was about 7000 poise measured at 240° C.and 1 rad/sec strain rate using the melt viscosity measurement proceduredescribed earlier. These islands-in-sea bicomponent fibers were madeusing a spinneret with 198 holes and a throughput rate of 0.85gms/minute/hole. The polymer ratio between “islands” polyester and “sea”sulfopolyester was 65% to 35%. These bicomponent fibers were spun usingan extrusion temperature of 280° C. for the polyester component and 260°C. for the sulfopolyester component. The bicomponent fiber contains amultiplicity of filaments (198 filaments) and was melt spun at a speedof about 530 meters/minute, forming filaments with a nominal denier perfilament of about 14. A finish solution of 24 weight % PT 769 finishfrom Goulston Technologies was applied to the bicomponent fiber using akiss roll applicator. The filaments of the bicomponent fiber were thendrawn in line using a set of two godet rolls, heated to 90° C. and 130°C. respectively, and the final draw roll operating at a speed of about1750 meters/minute, to provide a filament draw ratio of about 3.3×forming the drawn islands-in-sea bicomponent filaments with a nominaldenier per filament of about 4.5 or an average diameter of about 25microns. These filaments comprised the polyester microfiber “islands”having an average diameter of about 2.5 microns.

Example 16

The drawn islands-in-sea bicomponent fibers of Example 15 were cut intoshort length fibers of 3.2 millimeters and 6.4 millimeters cut lengths,thereby, producing short length bicomponent fibers with 64islands-in-sea cross-section configurations. These short cut bicomponentfibers comprised “islands” of polyester and “sea” of water dispersiblesulfopolyester polymer. The cross-sectional distribution of islands andsea was essentially consistent along the length of these short cutbicomponent fibers.

Example 17

The drawn islands-in-sea bicomponent fibers of Example 15 were soaked insoft water for about 24 hours and then cut into short length fibers of3.2 millimeters and 6.4 millimeters cut lengths. The water dispersiblesulfopolyester was at least partially emulsified prior to cutting intoshort length fibers. Partial separation of islands from the seacomponent was therefore effected, thereby, producing partiallyemulsified short length islands-in-sea bicomponent fibers.

Example 18

The short cut length islands-in-sea bicomponent fibers of Example 16were washed using soft water at 80° C. to remove the water dispersiblesulfopolyester “sea” component, thereby, releasing the polyestermicrofibers which were the “islands” component of the bicomponentfibers. The washed polyester microfibers were rinsed using soft water at25° C. to essentially remove most of the “sea” component. The opticalmicroscopic observation of the washed polyester microfibers showed anaverage diameter of about 2.5 microns and lengths of 3.2 and 6.4millimeters.

Example 19

The short cut length partially emulsified islands-in-sea bicomponentfibers of Example 17 were washed using soft water at 80° C. to removethe water dispersible sulfopolyester “sea” component, thereby, releasingthe polyester microfibers which were the “islands” component of thefibers. The washed polyester microfibers were rinsed using soft water at25° C. to essentially remove most of the “sea” component. The opticalmicroscopic observation of the washed polyester microfibers showedpolyester microfibers of average diameter of about 2.5 microns andlengths of 3.2 and 6.4 millimeters.

Comparative Example 20

Wet-laid hand sheets were prepared using the following procedure. 7.5gms of Albacel Southern Bleached Softwood Kraft (SBSK) fromInternational Paper, Memphis, Tenn., U.S.A. and 188 gms of roomtemperature water were placed in a 1000 ml pulper and pulped for 30seconds at 7000 rpm to produce a pulped mixture. This pulped mixture wastransferred into an 8 liter metal beaker along with 7312 gms of roomtemperature water to make about 0.1% consistency (7500 gms water and 7.5gms fibrous material) pulp slurry. This pulp slurry was agitated using ahigh speed impeller mixer for 60 seconds. Procedure to make the handsheet from this pulp slurry was as follows. The pulp slurry was pouredinto a 25 centimeters×30 centimeters hand sheet mold while continuing tostir. The drop valve was pulled, and the pulp fibers were allowed todrain on a screen to form a hand sheet. 750 grams per square meter (gsm)blotter paper was placed on top of the formed hand sheet, and theblotter paper was flattened onto the hand sheet. The screen frame wasraised and inverted onto a clean release paper and allowed to sit for 10minutes. The screen was raised vertically away from the formed handsheet. Two sheets of 750 gsm blotter paper were placed on top of theformed hand sheet. The hand sheet was dried along with the three blotterpapers using a Norwood Dryer at about 88° C. for 15 minutes. One blotterpaper was removed leaving one blotter paper on each side of the handsheet. The hand sheet was dried using a Williams Dryer at 65° C. for 15minutes. The hand sheet was then further dried for 12 to 24 hours usinga 40 kg dry press. The blotter paper was removed to obtain the dry handsheet sample. The hand sheet was trimmed to 21.6 centimeters by 27.9centimeters dimensions for testing.

Comparative Example 21

Wet-laid hand sheets were prepared using the following procedure. 7.5gms of Albacel Southern Bleached Softwood Kraft (SBSK) fromInternational Paper, Memphis, Tenn., U.S.A., 0.3 gms of Solivitose Npre-gelatinized quaternary cationic potato starch from Avebe, Foxhol,the Netherlands, and 188 gms of room temperature water were placed in a1000 ml pulper and pulped for 30 seconds at 7000 rpm to produce a pulpedmixture. This pulped mixture was transferred into an 8 liter metalbeaker along with 7312 gms of room temperature water to make about 0.1%consistency (7500 gms water and 7.5 gms fibrous material) to produce apulp slurry. This pulp slurry was agitated using a high speed impellermixer for 60 seconds. The rest of procedure for making hand sheet fromthis pulp slurry was same as in Example 20.

Example 22

Wet-laid hand sheets were prepared using the following procedure. 6.0gms of Albacel Southern Bleached Softwood Kraft (SBSK) fromInternational Paper, Memphis, Tenn., U.S.A., 0.3 gms of Solivitose Npre-gelatinized quaternary cationic potato starch from Avebe, Foxhol,the Netherlands, 1.5 gms of 3.2 millimeter cut length islands-in-seafibers of Example 16, and 188 gms of room temperature water were placedin a 1000 ml pulper and pulped for 30 seconds at 7000 rpm to produce afiber mix slurry. This fiber mix slurry was heated to 82° C. for 10seconds to emulsify and remove the water dispersible sulfopolyestercomponent in the islands-in-sea fibers and release polyestermicrofibers. The fiber mix slurry was then strained to produce asulfopolyester dispersion comprising the sulfopolyester and amicrofiber-containing mixture comprising pulp fibers and polyestermicrofiber. The microfiber-containing mixture was further rinsed using500 gms of room temperature water to further remove the waterdispersible sulfopolyester from the microfiber-containing mixture. Thismicrofiber-containing mixture was transferred into an 8 liter metalbeaker along with 7312 gms of room temperature water to make about 0.1%consistency (7500 gms water and 7.5 gms fibrous material) to produce amicrofiber-containing slurry. This microfiber-containing slurry wasagitated using a high speed impeller mixer for 60 seconds. The rest ofprocedure for making hand sheet from this microfiber-containing slurrywas same as in Example 20.

Comparative Example 23

Wet-laid hand sheets were prepared using the following procedure. 7.5gms of MicroStrand 475-106 micro glass fiber available from JohnsManville, Denver, Colo., U.S.A., 0.3 gms of Solivitose N pre-gelatinizedquaternary cationic potato starch from Avebe, Foxhol, the Netherlands,and 188 gms of room temperature water were placed in a 1000 ml pulperand pulped for 30 seconds at 7000 rpm to produce a glass fiber mixture.This glass fiber mixture was transferred into an 8 liter metal beakeralong with 7312 gms of room temperature water to make about 0.1%consistency (7500 gms water and 7.5 gms fibrous material) to produce aglass fiber slurry. This glass fiber slurry was agitated using a highspeed impeller mixer for 60 seconds. The rest of procedure for makinghand sheet from this glass fiber slurry was same as in Example 20.

Example 24

Wet-laid hand sheets were prepared using the following procedure. 3.8gms of MicroStrand 475-106 micro glass fiber available from JohnsManville, Denver, Colo., U.S.A., 3.8 gms of 3.2 millimeter cut lengthislands-in-sea fibers of Example 16, 0.3 gms of Solivitose Npre-gelatinized quaternary cationic potato starch from Avebe, Foxhol,the Netherlands, and 188 gms of room temperature water were placed in a1000 ml pulper and pulped for 30 seconds at 7000 rpm to produce a fibermix slurry. This fiber mix slurry was heated to 82° C. for 10 seconds toemulsify and remove the water dispersible sulfopolyester component inthe islands-in-sea bicomponent fibers and release polyester microfibers.The fiber mix slurry was then strained to produce a sulfopolyesterdispersion comprising the sulfopolyester and a microfiber-containingmixture comprising glass microfibers and polyester microfiber. Themicrofiber-containing mixture was further rinsed using 500 gms of roomtemperature water to further remove the sulfopolyester from themicrofiber-containing mixture. This microfiber-containing mixture wastransferred into an 8 liter metal beaker along with 7312 gms of roomtemperature water to make about 0.1% consistency (7500 gms water and 7.5gms fibrous material) to produce a microfiber-containing slurry. Thismicrofiber-containing slurry was agitated using a high speed impellermixer for 60 seconds. The rest of procedure for making hand sheet fromthis microfiber-containing slurry was same as in Example 20.

Example 25

Wet-laid hand sheets were prepared using the following procedure. 7.5gms of 3.2 millimeter cut length islands-in-sea fibers of Example 16,0.3 gms of Solivitose N pre-gelatinized quaternary cationic potatostarch from Avebe, Foxhol, the Netherlands, and 188 gms of roomtemperature water were placed in a 1000 ml pulper and pulped for 30seconds at 7000 rpm to produce a fiber mix slurry. This fiber mix slurrywas heated to 82° C. for 10 seconds to emulsify and remove the waterdispersible sulfopolyester component in the islands-in-sea fibers andrelease polyester microfibers. The fiber mix slurry was then strained toproduce a sulfopolyester dispersion and polyester microfibers. Thesulfopolyester dispersion was comprised of water dispersiblesulfopolyester. The polyester microfibers were rinsed using 500 gms ofroom temperature water to further remove the sulfopolyester from thepolyester microfibers. These polyester microfibers were transferred intoan 8 liter metal beaker along with 7312 gms of room temperature water tomake about 0.1% consistency (7500 gms water and 7.5 gms fibrousmaterial) to produce a microfiber slurry. This microfiber slurry wasagitated using a high speed impeller mixer for 60 seconds. The rest ofprocedure for making hand sheet from this microfiber slurry was same asin Example 20.

The hand sheet samples of Examples 20-25 were tested and properties areprovided in the following table.

TABLE 6 Porosity Basis Hand Sheet Greiner Tensile Weight ThicknessDensity (seconds/ Strength Elongation to Tensile × Ex. No. Composition(gsm) (mm) (gm/cc) 100 cc) (kg/15 mm) Break (%) Elongation 20 100% SBSK94 0.45 0.22 4 1.0 7 7 21 SBSK + 4% 113 0.44 0.22 4 1.5 7 11 Starch 2280% SBSK + 116 0.30 0.33 4 2.2 9 20 Starch + 20% 3.2 mm polyestermicrofibers of Example 19 23 100% Glass 103 0.68 0.15 4 0.2 15 3MicroStrand 475-106 + Starch 24 50% Glass 104 0.45 0.22 4 1.4 7 10Microstand 475-106 + 50% 3.2 mm polyester microfibers of Example 19 +Starch 25 100% 3.2 mm 80 0.38 0.26 4 3.0 15 44 polyester microfibers ofExample 19

The hand sheet basis weight was determined by weighing the hand sheetand calculating weight in grams per square meter (gsm). Hand sheetthickness was measured using an Ono Sokki EG-233 thickness gauge andreported as thickness in millimeters. Density was calculated as weightin grams per cubic centimeter. Porosity was measured using a GreinerPorosity Manometer with 1.9×1.9 cm square opening head and 100 cccapacity. Porosity is reported as average time in seconds (4 replicates)for 100 cc of water to pass through the sample. Tensile properties weremeasured using an Instron Model™ for six 30 mm×105 mm test strips. Anaverage of six measurements is reported for each example. It can beobserved from these test data that significant improvement in tensileproperties of wet-laid fibrous structures is obtained by the addition ofpolyester microfibers of the current invention.

Example 26

The sulfopolyester polymer of Example 13 was spun into bicomponentislands-in-the-sea cross-section fibers with 37 islands fibers using abicomponent extrusion line. The primary extruder fed Eastman F61HCpolyester to form the “islands” in the islands-in-the-sea cross-sectionstructure. The secondary extruder fed the water dispersiblesulfopolyester polymer to form the “sea” in the islands-in-seabicomponent fiber. The inherent viscosity of the polyester was 0.61 dL/gwhile the melt viscosity of dry sulfopolyester was about 7000 poisemeasured at 240° C. and 1 rad/sec strain rate using the melt viscositymeasurement procedure described previously. These islands-in-seabicomponent fibers were made using a spinneret with 72 holes and athroughput rate of 1.15 gms/minute/hole. The polymer ratio between“islands” polyester and “sea” sulfopolyester was 2 to 1. Thesebicomponent fibers were spun using an extrusion temperature of 280° C.for the polyester component and 255° C. for the water dispersiblesulfopolyester component. This bicomponent fiber contained amultiplicity of filaments (198 filaments) and was melt spun at a speedof about 530 meters/minute forming filaments with a nominal denier perfilament of 19.5. A finish solution of 24% by weight PT 769 finish fromGoulston Technologies was applied to the bicomponent fiber using a kissroll applicator. The filaments of the bicomponent fiber were then drawnin line using a set of two godet rolls, heated to 95° C. and 130° C.respectively, and the final draw roll operating at a speed of about 1750meters/minute, to provide a filament draw ratio of about 3.3× formingthe drawn islands-in-sea bicomponent filaments with a nominal denier perfilament of about 5.9 or an average diameter of about 29 microns. Thesefilaments comprised the polyester microfiber islands of average diameterof about 3.9 microns.

Example 27

The drawn islands-in-sea bicomponent fibers of Example 26 were cut intoshort length bicomponent fibers of 3.2 millimeters and 6.4 millimeterscut length, thereby, producing short length fibers with 37islands-in-sea cross-section configurations. These fibers comprised“islands” of polyester and “sea” of water dispersible sulfopolyesterpolymers. The cross-sectional distribution of “islands” and “sea” wasessentially consistent along the length of these bicomponent fibers.

Example 28

The short cut length islands-in-sea fibers of Example 27 were washedusing soft water at 80° C. to remove the water dispersiblesulfopolyester “sea” component, thereby, releasing the polyestermicrofibers which were the “islands” component of the bicomponentfibers. The washed polyester microfibers were rinsed using soft water at25° C. to essentially remove most of the “sea” component. The opticalmicroscopic observation of the washed polyester microfibers had anaverage diameter of about 3.9 microns and lengths of 3.2 and 6.4millimeters.

Example 29

The sulfopolyester polymer of Example 13 was spun into bicomponentislands-in-the-sea cross-section fibers with 37 islands fibers using abicomponent extrusion line. The primary extruder fed polyester to formthe “islands” in the islands-in-the-sea fiber cross-section structure.The secondary extruder fed the water dispersible sulfopolyester polymerto form the “sea” in the islands-in-sea bicomponent fiber. The inherentviscosity of the polyester was 0.52 dL/g while the melt viscosity of thedry water dispersible sulfopolyester was about 3500 poise measured at240° C. and 1 rad/sec strain rate using the melt viscosity measurementprocedure described previously. These islands-in-sea bicomponent fiberswere made using two spinnerets with 175 holes each and throughput rateof 1.0 gms/minute/hole. The polymer ratio between “islands” polyesterand “sea” sulfopolyester was 70% to 30%. These bicomponent fibers werespun using an extrusion temperature of 280° C. for the polyestercomponent and 255° C. for the sulfopolyester component. The bicomponentfibers contained a multiplicity of filaments (350 filaments) and weremelt spun at a speed of about 1000 meters/minute using a take-up rollheated to 100° C. forming filaments with a nominal denier per filamentof about 9 and an average fiber diameter of about 36 microns. A finishsolution of 24 weight % PT 769 finish was applied to the bicomponentfiber using a kiss roll applicator. The filaments of the bicomponentfiber were combined and were then drawn 3.0× on a draw line at draw rollspeed of 100 m/minute and temperature of 38° C. forming drawnislands-in-sea bicomponent filaments with an average denier per filamentof about 3 and average diameter of about 20 microns. These drawnisland-in-sea bicomponent fibers were cut into short length fibers ofabout 6.4 millimeters length. These short length islands-in-seabicomponent fibers were comprised of polyester microfiber “islands” ofaverage diameter of about 2.8 microns.

Example 30

The short cut length islands-in-sea bicomponent fibers of Example 29were washed using soft water at 80° C. to remove the water dispersiblesulfopolyester “sea” component, thereby, releasing the polyestermicrofibers which were the “islands” component of the fibers. The washedpolyester microfibers were rinsed using soft water at 25° C. toessentially remove most of the “sea” component. The optical microscopicobservation of washed fibers showed polyester microfibers of averagediameter of about 2.8 microns and lengths of about 6.4 millimeters.

Example 31

Wet-laid microfiber stock hand sheets were prepared using the followingprocedure. 56.3 gms of 3.2 millimeter cut length islands-in-seabicomponent fibers of Example 16, 2.3 gms of Solivitose Npre-gelatinized quaternary cationic potato starch from Avebe, Foxhol,the Netherlands, and 1410 gms of room temperature water were placed in a2 liter beaker to produce a fiber slurry. The fiber slurry was stirred.One quarter amount of this fiber slurry, about 352 ml, was placed in1000 ml pulper and pulped for 30 seconds at 7000 rpm. This fiber slurrywas heated to 82° C. for 10 seconds to emulsify and remove the waterdispersible sulfopolyester component in the islands-in-sea bicomponentfibers and release polyester microfibers. The fiber slurry was thenstrained to produce a sulfopolyester dispersion and polyestermicrofibers. These polyester microfibers were rinsed using 500 gms ofroom temperature water to further remove the sulfopolyester from thepolyester microfibers. Sufficient room temperature water was added toproduce 352 ml of microfiber slurry. This microfiber slurry wasre-pulped for 30 seconds at 7000 rpm. These microfibers were transferredinto an 8 liter metal beaker. The remaining three quarters of the fiberslurry were similarly pulped, washed, rinsed and re-pulped andtransferred to the 8 liter metal beaker. 6090 gms of room temperaturewater was then added to make about 0.49% consistency (7500 gms water and36.6 gms of polyester microfibers) to produce a microfiber slurry. Thismicrofiber slurry was agitated using a high speed impeller mixer for 60seconds. The rest of procedure for making hand sheet from thismicrofiber slurry was same as in Example 20. The microfiber stock handsheet with the basis weight of about 490 gsm was comprised of polyestermicrofibers of average diameter of about 2.5 microns and average lengthof about 3.2 millimeters.

Example 32

Wet-laid hand sheets were prepared using the following procedure. 7.5gms of polyester microfiber stock hand sheet of Example 31, 0.3 gms ofSolivitose N pre-gelatinized quaternary cationic potato starch fromAvebe, Foxhol, the Netherlands, and 188 gms of room temperature waterwere placed in a 1000 ml pulper and pulped for 30 seconds at 7000 rpm.The microfibers were transferred into an 8 liter metal beaker along with7312 gms of room temperature water to make about 0.1% consistency (7500gms water and 7.5 gms fibrous material) to produce a microfiber slurry.This microfiber slurry was agitated using a high speed impeller mixerfor 60 seconds. The rest of procedure for making hand sheet from thisslurry was same as in Example 20. A 100 gsm wet-laid hand sheet ofpolyester microfibers was obtained having an average diameter of about2.5 microns.

Example 33

The 6.4 millimeter cut length islands-in-sea bicomponent fibers ofExample 29 were washed using soft water at 80° C. to remove the waterdispersible sulfopolyester “sea” component, thereby, releasing thepolyester microfibers which were the “islands” component of thebicomponent fibers. The washed polyester microfibers were rinsed usingsoft water at 25° C. to essentially remove most of the “sea” component.The optical microscopic observation of the washed polyester microfibersshowed an average diameter of about 2.5 microns and lengths of 6.4millimeters.

Example 34

The short cut length islands-in-sea bicomponent fibers of Example 16,Example 27 and Example 29 were washed separately using soft water at 80°C. containing about 1% by weight based on the weight of the bicomponentfibers of ethylene diamine tetra acetic acid tetra sodium salt (Na₄EDTA) from Sigma-Aldrich Company, Atlanta, Ga. to remove the waterdispersible sulfopolyester “sea” component, thereby, releasing thepolyester microfibers which were the “islands” component of thebicomponent fibers. The addition of at least one water softener, such asNa₄ EDTA, aids in the removal of the water dispersible sulfopolyesterpolymer from the islands-in-sea bicomponent fibers. The washed polyestermicrofibers were rinsed using soft water at 25° C. to essentially removemost of the “sea” component. The optical microscopic observation ofwashed polyester microfibers showed excellent release and separation ofpolyester microfibers. Use of a water softing agent, such as Na₄ EDTA inthe water prevents any Ca⁺⁺ ion exchange on the sulfopolyester which canadversely affect the water dispersiblity of sulfopolyester. Typical softwater may contain up to 15 ppm of Ca⁺⁺ ion concentration. It isdesirable that the soft water used in the processes described hereshould have essentially zero concentration of Ca⁺⁺ and othermulti-valent ions or alternately use sufficient amount of watersoftening agent, such as Na₄ EDTA, to bind these Ca⁺⁺ ions and othermulti-valent ions. These polyester microfibers can be used in preparingthe wet-laid sheets using the procedures of examples disclosedpreviously.

Example 35

The short cut length islands-in-sea bicomponent fibers of Example 16 andExample 27 were processed separately using the following procedure. 17grams of Solivitose N pre-gelatinized quaternary cationic potato starchfrom Avebe, Foxhol, the Netherlands were added to the distilled water.After the starch was fully dissolved or hydrolyzed, then 429 grams ofshort cut length islands-in-sea bicomponent fibers were slowly added tothe distilled water to produce a fiber slurry. A Williams RotaryContinuous Feed Refiner (5 inch diameter) was turned on to refine or mixthe fiber slurry in order to provide sufficient shearing action for thewater dispersible sulfopolyester to be separated from the polyestermicrofibers. The contents of the stock chest were poured into a 24 literstainless steel container, and the lid was secured. The stainless steelcontainer was placed on a propane cooker and heated until the fiberslurry began to boil at about 97° C. in order to remove thesulfopolyester component in the island-in-sea fibers and releasepolyester microfibers. After the fiber slurry reached boiling, it wasagitated with a manual agitating paddle. The contents of the stainlesssteel container were poured into a 27 in×15 in×6 in deep False BottomKnuche with a 30 mesh screen to produce a sulfopolyester dispersion andpolyester microfibers. The sulfopolyester dispersion comprised water andwater dispersible sulfopolyester. The polyester microfibers were rinsedin the Knuche for 15 seconds with 10 liters of soft water at 17° C., andsqueezed to remove excess water.

20 grams of polyester microfiber (dry fiber basis) was added to 2000 mlof water at 70° C. and agitated using a 2 liter 3000 rpm ¾ horse powerhydropulper manufactured by Hermann Manufacturing Company for 3 minutes(9,000 revolutions) to make a microfiber slurry of 1% consistency.Handsheets were made using the procedure described previously in Example20.

The optical and scanning electron microscopic observation of thesehandsheets showed excellent separation and formation of polyestermicrofibers.

Example 36

This example covers opening of bicomponent islands in the sea (INS)fibers extruded in a manner to form 4.5 denier per filament fibers witheach filament having 37 PET islands comprised of Eastman F-61HCpolyester and a sea fraction comprised of Eastman sulfopolyesterpolymer. The ratio of polyester component to sulfopolyester seacomponent was 70 PET/30 sulfopolyester. The fibers were produced using abicomponent islands in the sea spin pack manufactured by Hills Inc.(Melbourne, Fl). Extrusion and draw conditions were adjusted to achievea nominal 22 micron overall starting fiber where a 2.0 micron averagediameter of the individual islands was targeted. Drawn yarns wereproduced which were cut into 1.5 mm long staple fibers. The bicomponentfibers were cut to a 1.5 mm overall length to product cut bicomponentfibers, and were used in evaluation to produce opened microfiberscomprised of individual 3.0 micron individual PET islands after theopening process.

Bicomponent fibers comprised of 37 INS filaments cut to 1.5 mm lengthwere opened using a batch opening process to remove the sulfopolyestersea component which was the binder holding together the 37 PET islandsin the cut bicomponent fiber. In the opening process of Example 36, a 20kg. charge of deionized water was added to a 10 gallon laboratoryhydropulper (Adirondack Machinery Co.) and heated to 79° C. by additionof low pressure steam while agitating using a 30% speed setting. Whenthe deionized water reached 79° C., 400 grams of the 37 INS cutbicomponent fiber were quickly added to the agitated water, and a timerstarted after all the cut bicomponent fiber was added. After 10 secondsof agitation, a nominal 400 cc sample of the opened microfiber slurrywas withdrawn and immediately screened using a colander to quicklyseparate the microfiber product from the first mother liquor containingsulfopolyester polymer that was removed during the 10 second contact in79° C. water. The microfiber product sample was pressed against thescreen to dewater the microfiber product down to about 20%-25% moisturecontent. Samples were withdrawn from the hydropulper after 20 seconds,after 60 seconds, and after 120 seconds mixing time, and each sample wassimilarly screened to recover the first mother liquor separated from themicrofiber product.

The degree of removal of the sulfopolyester sea component was evaluatedby measuring the solids content of the first mother liquor recoveredfrom each of the four test samples. In the process, the % solids levelin the final samples taken after long 120 seconds contact time representconditions where the maximum amount of sulfopolyester is removed fromthe starting cut bicomponent fiber near quantitative removal. The solidscontent in each sample was measured by measuring the weight of a 3inch×5 inch aluminum pan (+/−0.001 g) and then adding 100.0 grams of thefirst mother liquor sample containing the removed sulfopolyester. Waterwas boiled off using a hot plate at a moderate rate to prevent bumpingthe liquid out of the pan. After removing almost all of the water on ahot plate, the sample pan containing the polymer residue was furtherdried to a uniform moisture level by placing the pan in a forced airoven at 180° C. for 5 minutes to condition the residue to uniformmoisture content. The pan was re-weighed (+/−0.001 g), and the weight ofthe residue calculated by subtracting the starting pan weight. Solidscontent was calculated by dividing the residue weight by the startingsample weight.

The variation of solids in the first mother liquor recovered from theopening process of Example 36 is shown in FIG. 8.

After the sulfopolyester polymer is quantitatively removed from the cutmulticomponent fibers, the solids residue in the first mother liquorwill not increase. Test results found minimal increase in solids contentin the first mother liquor recovered after the first 10 second samplewas withdrawn. Differences in the solids level of samples withdrawn at20 seconds, 60 seconds, and 120 seconds are within testing variability.Removal efficiency after only 10 seconds contact in 79° C. water was 95%or within 5% of the removal level considered quantitative. In Example36, the sulfopolyester sea component was effectively removed from 37 INScut bicomponent fiber at 4.5 dpf using contact time of 15 seconds orshorter in agitated water at 79° C.

Example 37

The process of Example 36 was repeated with the variation that the speedsetting of the Adirondack hydropulper was increased from 30% setting toan 80% setting to improve the mixing of the 37 INS cut bicomponent fiberin the deionized water heated to 79° C. A sulfopolyester removal profilesimilar to FIG. 8 was observed where the % solids value of the initial10 second sample was within the testing precision of the later solidsvalues, indicating quantitative sulfopolyester removal after 10 secondscontact time at 79° C.

Example 38

The 37 INS bicomponent fiber opening process was run in the same manneras Example 36 with the modification that the temperature of thedeionized water contacting the cut bicomponent fiber was reduced to 74°C. or 5° C. lower than the temperature used in Example 36. The variationof solids in the first mother liquor recovered from the opening processof this Example 38 is shown in FIG. 9.

Samples withdrawn after 20 seconds, 60 seconds, and 120 secondsdisplayed solids content consistent with quantitative removal of thesulfopolyester from the cut bicomponent fiber. Even at 10 secondscontact at 74° C., sulfopolyester removal was within 5% of quantitativeremoval, indicating fast removal of the sea component from the cutbicomponent fiber at 74° C.

Example 39

Cut bicomponent fibers of Example 36 having 37 INS construction and 4.5dpf fineness were opened in a similar manner as described in Example 36where the agitation of the hydropulper was set at a 50% setting and thetemperature of the deionized water used in the opening step was reducedto 68° C. Samples were withdrawn after 15 seconds, 30 seconds, 60seconds, and 120 seconds conditioning of the cut bicomponent fibers inthe agitated 68° C. water. The first mother liquor recovered from eachof the samples was analyzed for sulfopolyester content by measuring thesolids content using the method described in Example 36. Thesulfopolyester content in the first mother liquor as a function of theconditioning time is displayed in FIG. 10. The time required for thesolids level to reach an asymptote, where sulfopolyester removalapproaches quantitative levels, is an indicator of the speed of theopening step.

At 68° C., quantitative removal of the sulfopolyester sea component wasachieved after 60 seconds or longer contact time in 68° C. water butremoval after short (15 seconds) contact was far from quantitative (80%of maximum value) and only after 30 seconds approaching quantitativeremoval. In comparison, Examples 36 through Examples 38 exhibited nearquantitative removal of the sulfopolyester sea component in samplestaken after 10 seconds contact time where the water temperature in theseexamples was also higher than in Example 39. Example 39 demonstrates abicomponent fiber opening process that would be effective if longerfiber/hot water contact times are applied, on the order of 60 seconds orlonger at 68° C., but where incomplete removal of the sea componentwould occur at shorter conditioning times.

Comparative Example 40

A bicomponent fiber opening process was run in the same manner asExample 36, but where the temperature of the deionized water used duringthe opening process was further reduced to 63° C. Samples were withdrawnafter 15 seconds, 30 seconds, 60 seconds, and 120 seconds, and the firstmother liquor recovered from each sample was analyzed for solids contentto determine the amount of sulfopolyester removed and the openingefficiency. The rate of sulfopolyester removal is displayed in FIG. 11.This response demonstrates slower removal behavior for thesulfopolyester sea component.

About ⅔ of the sulfopolyester sea component was removed from the cutbicomponent fibers after 15 seconds contact time, and about 85% after 30seconds contact. Removal levels were high at 60 seconds contact time butnot quantitative. Opening times in excess of 2 minutes would be requiredat 63° C. to assure levels of sea component removal from the cutbicomponent fibers that would be considered quantitative. The primaryeffect of the opening process was to remove the sea component to a levelthat would be considered quantitative and in this regard the slowremoval rates measured in Comparative Example 40 demonstrated openingconditions that would be slower on a commercial scale for opening cutbicomponent fibers comprised of sulfopolyester as the removablecomponent. In Comparative Example 40, the agitation setting was 30%where a higher level of agitation or turbulence during the openingprocess can reduce the time required to affect quantitative opening anda decrease in mixing energy can slow down the opening process andrequire even longer times to affect complete removal of thesulfopolyester component.

The removal rates documented in this and all previous Examples are basedon cut bicomponent fibers comprised of sulfopolyester as the removablecomponent. If the removable component is replaced with a polymer typewhich can be removed (dissolved or emulsified) into the water phaseeither more easily or with greater difficulty, the temperature of theopening process will vary depending on the characteristics of theremovable polymer. These examples serve to illustrate removalcharacteristics of bicomponent fibers containing a specific type ofremovable sulfopolyester polymer but are not meant to be limiting interms of opening conditions suitable for bicomponent fibers comprised ofdifferent types of removable polymers.

Comparative Example 41

The same procedure described in Example 36 was used in ComparativeExample 41 where sufficient CaCl₂ was added to the deionized watercharge to add Ca⁺² cations to the water phase at a level of 20 ppm byweight, and the temperature of the opening process was 77° C. Thesulfopolyester removal profile for fiber opening under these conditionsis displayed in FIG. 12.

In comparison to Examples 36 and 37, carried out at a similar openingtemperature but using deionized water, the sulfopolyester removal ratesin Comparative Example 41 were much slower. In both previous examples,near quantitative removal of sulfopolyester was recorded after about 10seconds contact time in deionized water at 79° C. In Comparative Example41, only about 90% removal was accomplished after 30 seconds withsimilar levels of agitation.

Compared to the removal characteristics in Examples 36, 37, and 38, thesulfopolyester removal characteristics in Comparative Example 41 wereslower, where only 90% removal was measured after 30 seconds inComparative Example 41 while near quantitative removal was measuredafter 10-15 seconds in the prior examples. The removal characteristicsof Comparative Example 41 were similar to the characteristics measuredfor Comparative Example 40 (FIG. 4) carried out at a 14° C. loweropening temperature but using deionized water with no hard cations.Comparative Example 41 serves to illustrate that the hardness of thewater used in the opening process strongly influences the contact timeand temperature required to open bicomponent fibers comprised of waterdispersible sulfopolyester components, where 20 ppm Ca+2 hardness isborderline and higher levels may make complete fiber opening very slowor not possible.

Example 42 Continuous Bicomponent Fiber Opening Process

Previous Examples 36 through 39 illustrate the use of a batch typeopening process to remove a water dispersible polymer fraction frombicomponent fibers. In commercial production, a continuous type processis generally utilized because of the higher efficiencies afforded bycontinuous operation. The major improvement in efficiency is due to theelimination of the batch charge and batch discharge phase of the overallbatch cycle which removes a substantial amount of processing time duringthe batch cycle and which in turn permits the same amount of productionto be accomplished using smaller equipment sizes.

There are two primary types of continuous operation applicable to anopening process for bicomponent fibers consisting of removing orextracting a water dispersible polymer from a water non-dispersiblepolymer fiber material into an aqueous phase. The first type process isthe continuous stirred tank reactor (CSTR) in which the water and cutmulticomponent fiber can be added to a stirred tank at constantproportion and constant feed rate while the opened microfiber slurry canbe removed from the stirred tank at the same equal mass flow rate inorder to maintain a constant level of cut multicomponent fiber slurry inthe stirred tank.

The disadvantage of a CSTR is the residence time distribution of the cutmulticomponent fibers inside the stirred tank during the process. In abatch type process, all product is processed for nominally the sameamount of time during the batch cycle between the end of the chargephase and the start of the discharge phase. In a CSTR, the cutmulticomponent fiber added to the stirred tank is mixed with material inthe tank, processed for varying lengths of time, and the materialdischarged from the tank is comprised of microfibers which were treatedinside the tank for varying lengths of time. The amount of time thatmicrofiber stays inside the tank during the CSTR opening process isdefined by a statistical average where center point of the statisticalaverage is the average time that the microfiber material resides insidethe tank. This statistical average residence time (RT) that themicrofiber resides inside the stirred tank is defined by the quantityRT=V_(t)/Q where V_(t) is the total volume of liquid contained withinthe stirred tank and Q is the volumetric flow of liquid out of the tankduring continuous operation.

The problem issue with a CSTR for continuous operation is that based onthis statistical distribution some of the cut multicomponent fiber addedto the tank resides inside for only short periods, which may beinsufficient for complete fiber opening, while at the other end of thedistribution, some of the cut multicomponent fibers remain in the tankfor much longer than the targeted average RT during which time the smalldiameter microfibers can be mechanically damaged by excessive mixingover the prolonged period inside the tank.

For this reason, another method for a continuous fiber opening processis a plug flow process often used in chemical processing. In this typeprocessing, a fluid is added to a process vessel at a constant rate, andeach element of fluid added to the vessel travels through the vessel atnominally the same velocity, so that all elements of fluid are containedinside the vessel for nominally the same amount of time. Compared to aCSTR, a plug flow opening process can eliminate the problems associatedwith a portion of the cut multicomponent fibers residing inside theprocess vessel for insufficient time to become fully opened and aportion of the fiber residing in the tank for excessive times leading tomechanical damage of the microfibers.

In one embodiment of a plug flow opening process for bicomponent fibers,the plug flow vessel can be a long section of pipe in which hot aqueousmulticomponent fiber slurry is added to one end of the pipe section at aconstant volumetric flow rate, the multicomponent fiber slurry passesthrough the pipe at a nominally constant flow velocity, and themulticomponent fiber slurry exits the other end of the process pipeafter a residence time inside the pipe defined by dividing the totalvolume contained inside the process pipe by the volumetric flow rate ofthe multicomponent fiber slurry into the process pipe.

General Plug Flow Bicomponent Fiber Opening Process

Several examples are provided of a continuous plug flow process foropening cut multicomponent fiber comprised of a water dispersiblesulfopolyester phase which is removed from the cut multicomponent duringthe opening process. The specific process steps in the overall plug flowoperation can be placed in the following categories:

-   -   1) Concentrated cold, cut multicomponent slurry prepared from        cut multicomponent fiber;    -   2) Production of a hot, treated aqueous stream for mixing with        the cold, cut multicomponent fiber slurry;    -   3) Combination of streams (1) and (2) to produce a hot        multicomponent fiber slurry;    -   4) Fiber opening as the hot multicomponent fiber slurry (3)        flows in plug flow through a process pipe to produce an opened        microfiber slurry; and    -   5) Separation of a microfiber product stream from the opened        microfiber slurry containing removed sulfopolyester polymer        using a screen filtration device.

A more detailed description of each of these specific process steps islisted used in this example is provided below.

1) Preparation of a Cold, Cut Multicomponent Fiber Slurry from CutMulticomponent Fiber

City water containing nominal 25 ppm hard cations passed through a watersoftener to reduce the concentration of hard cations to less than 1 ppm.Softened water at about 18° C. was continuously metered into a stirredtank containing 10 gallons fluid level at a target flow rate to maintaina constant fluid level in the stirred tank. Cut multicomponent fiber ofExample 36 was added continuously to the well stirred mix tank at aconstant rate and proportion relative to water flow in order to generatea cold, cut multicomponent fiber slurry containing cut multicomponentfiber at the target concentration. Cold, cut multicomponent fiber slurryof cut multicomponent fiber was pumped out of the cold slurry mix tankusing a variable speed centrifugal pump in order to pump out the coldcut multicomponent fiber slurry at the same rate that ingredients arefed to the mix tank in order to maintain a constant level in the coldslurry mix tank.

The operating principle of the cold slurry process step is to dispersethe cut multicomponent fibers into cold water containing a lowconcentration of hard cations in such a way that the agitation providedis sufficient to hold the cut multicomponent fibers in suspension andprevent the cut multicomponent fibers from settling in the mix tank.Both the water temperature and residence time of the cut multicomponentfibers in the cold slurry tank are designed to prevent significantsulfopolyester removal in the cold slurry tank and minimize mechanicaldamage to the fibers in the tank.

2) Preparation of a Hot, Treated Aqueous Stream for the Fiber OpeningProcess

Deionized water was metered to inlet of a steam heated tubular heatexchanger using a micro-motion flow controller to maintain a constanthot water flow at the targeted rate. Steam was applied to the heatexchanger to heat the deionized water stream to an outlet temperature of96° C.-98° C. at the targeted flow rate.

Hot deionized water exiting the heat exchanger was channeled to a mixingtee and combined with the cold, cut multicomponent fiber slurry streampreviously described.

3) Combination of Hot Water Stream and Cold Fiber Slurry Stream

The hot water stream (2) and cold, cut multicomponent fiber slurry (1)were combined in a 1½ inch pipe tee by combining both streamscontinuously using only the turbulence in the fluid flow to homogenouslymix both streams and allowing the combined stream to continuously flowout of the mixing tee into a fiber opening section constructed of 1½inch Schedule 40 CPVC pipe. The ratio of hot water (98° C.) flow rate tocold, multicomponent fiber slurry (18° C.) was selected so that thetemperature of the combined stream is sufficiently high to cause rapidopening or removal of sulfopolyester polymer from the cut multicomponentfiber. Target temperature for the combined stream are in the nominalrange range 70° C. to 80° C. to cause rapid sulfopolyester during flowthrough the 1½ inch pipe opening device.

4) Fiber Opening in Plug Flow Through 1½ Inch Pipe Device

The opening device was constructed of (5) ten foot section of 1½ inchCPVC pipe which afforded a total 55 feet of flow length from inlet tooutlet. The contained pipe volume of 0.78 ft³ was calculated. Thetypical flow rate of the combined fiber slurry stream was about 1.1ft³/min., translating to a nominal residence time of 40 seconds as thecombined fiber slurry flowed through the plug flow opening device.

Examples are provided where the length of the plug flow pipe section wasextended to 110 feet total length to afford a total residence time of 80seconds during the fiber opening step.

5) Opened Microfiber Recovery

Baskets 18″ in diameter by 12″ tall were constructed out of perforatedsteel sheet metal with 3/16″ perforations. The holes were sufficientlysmall to prevent the microfiber product exiting the opening step to passthrough but allow the process water to drain out. Effluent from the 1½″pipe opening device was channeled directly into the baskets to allow thefirst mother liquor containing sulfopolyester to drain through andrecover the wet cake comprised of opened PET microfibers.

A continuous opening of 37 islands in the sea bicomponent fibers wasconducted by applying the general plug flow bicomponent fiber openingprocess described previously to the cut bicomponent fiber of Example 36.In this example, a cold, cut bicomponent fiber slurry was produced bypassing crude city water at 18° C. through a water softening unit toremove hard cations to less than 1 ppm and metering the softened waterat about 2.3 gallons/minute (gpm) or nominal 9 kg./minute into a stirredtank holding previously treated water at a nominal 12 gallon liquidlevel. As the cold water was added to the tank, it was pumped out fromthe bottom of the tank and to the mixing tee and plug flow pipe sectionof the opening process using a variable speed centrifugal pump with 4inch impeller, where the speed of the pump was adjusted to pump liquidout of the tank at the same nominal 2.3 gpm rate at which it was addedin order to maintain a constant tank level.

As water was added to the tank, the 37 INS cut bicomponent fiber ofExample 36 was continuously added to the liquid in the mix tank througha port in the top of the tank at a rate of 325 grams/minute whileapplying sufficient agitation to the bicomponent fiber slurry in thetank to maintain the starting cut bicomponent fiber in suspension insidethe tank and prevent settling. During continuous operation, theconcentration of the cut multicomponent fiber in the cold,multicomponent fiber slurry approached a steady state slurryconcentration of about 3.5% fibers in water by weight.

The hot water stream for the process of Example 42 was generated byusing a Pic heater device where deionized water was metered through amicro-motion flow control device at a nominal rate of 6 gpm or 22kg/min. to the inlet of a steam heated heat exchanger. The outlettemperature of the deionized water exiting the heat exchanger wascontrolled at 97° C. by a temperature controller which adjusted steampressure to the jacket of the heat exchanger in order to regulate theoutlet temperature.

The hot water stream exiting the Pic heater flowed to the inlet of themixing tee where it combined with the flow stream from the cold,bicomponent fiber slurry tank before passing through the plug flowcontacting device. Total combined flow of the hot water stream and thecold, bicomponent fiber slurry stream was 8.3 gpm or 31 kg/min. The hotwater stream amounted to about 71% of the combined stream by weight.Temperature of the combined stream exiting the mixing tee was measuredto be 75° C. where the outlet temperature was controlled by theindividual temperatures of each stream and the relative proportion atwhich the streams were combined in the mixing tee. Likewise, theconcentration of the cut bicomponent fiber in the combined streamdecreased from 3.5% in the cold slurry to 1.0% in the combined stream,based on the proportion of each individual stream before mixing.

The combined fiber slurry stream containing 1.0 weight % cut bicomponentfiber at 75° C. temperature was channeled to the inlet of the plug flowopening device. The plug flow opening device consisted of (5) sectionsof 1½ inch Schedule 40 CPVC pipe having a total flow length of 55 feet.The mean plug flow velocity of the cut bicomponentfiber slurry throughthe pipe section was calculated to be 1.2 ft/sec, and the mean residencetime of the cut bicomponent slurry in the plug flow section wascalculated to be 45 seconds under the flow conditions applied in Example42. Calculation of the Reynolds number for pipe flow under theseconditions determined that the flow is in the turbulent regime where themixing energy afforded by turbulent flow assisted in the removal of thesulfopolyester polymer from the cut bicomponent fibers to produce anopened microfiber slurry. Essentially quantitative removal ofsulfopolyester from the bicomponent precursor fibers in the 45 secondcontact time inside the pipe section was a process requirement in thisexample.

Microfibers were filtered out of the opened microfiber slurry exitingthe plug flow contacting section using a basket filter with 3/16″perforations (40% of surface area). Compared to the microfibers ofExamples 36-38, the microfibers of Example 42 filtered less effectivelyin terms of slower permeation rates and fine fibers passing through thefilter. The effect was caused by lesser entanglement of the microfibersduring flow in the plug flow section of Example 42. The turbulent mixingin Example 42 can deform and entangle the microfibers to a lesser degreethan the vigorous agitation in the former Examples and dewateringscreens with smaller opening may be required for the microfibers ofExample 42.

The texture of the microfibers of Example 42 was dramatically changedfrom the texture of the starting 1.5 mm cut bicomponent fiber. Thetexture of the starting wet, cut bicomponent fiber was very coarse andgritty. The texture of the filtered microfibers of Example 42 was smoothto the point of being slimy in feel, indicating a dramatic change infiber characteristics.

The microfibers of Example 42 were re-dispersed in additional water tolow dilution and applied to microscope slides for characterization.Microscopic examination found the microfibers of Example 42 to be veryfine fibers with nominal fiber diameters of about 3 microns,corresponding to the starting diameter of the starting PET islandsdomains in the 37 island in the sea cut bicomponent fiber. Microscopicexamination found little evidence of residual sea material bonding the 3micron island fibers together in the product fibers. Only a smallfraction of incompletely opened fibers was noted, comprised of multipleisland fibrils bonded together by residual sea material incompletelyremoved during the process of Example 42.

The microfibers of Example 42 were evaluated by re-dispersing filteredmicrofiber product in water at a 0.02% concentration of solid fiber inwater and converting the dilute fiber solution to paper hand sheetsamples using a standard 6.25 inch diameter TAPPI sheet former.Comparative tests were conducted using microfibers opened by a batchopening process described in Examples 36-38. The microfibers of Example42 were noted to be qualitatively equivalent to fibers opened by a batchprocess in terms of both processing characteristics when re-dispersed tolow solids slurry in water and in terms of sheet characteristics whenthe re-dispersed dilute fiber slurries were converted to paper likeproducts by high dilution forming techniques using a conventional 6.25inch diameter TAPPI sheet former.

Example 43

In Example 43, the process of Example 42 was conducted where theaddition rate of cut, bicomponent fiber to the cold slurry tank wasincreased from 325 grams/min to 475 grams/minute amounting to anincrease in solids level in the cold slurry stream from 3.5 weight % to5.0 weight %. The nominal concentration of the cut bicomponent fiber inthe hot slurry entering the plug flow pipe section was 1.5 weight %. Theincreased cut bicomponent fiber level in both the cold slurry sectionand the combined hot slurry section did not cause any notable processingdifficulties relative to the process of Example 42.

The microfibers of Example 43 were characterized in the same manner asdescribed in Example 42 and were found to be functionally equivalent interms of degree of opening and subsequent behavior when re-dispersedinto dilute fiber slurries and converted into sheet samples byconventional high dilution paper forming techniques.

Example 44

In Example 44, the process of Example 42 was conducted where the flowrate of cold water to the cold slurry tank was decreased from 2.3 gpm toabout 2.0 gpm and the flow rate of 97° C. water from the Pic heater tothe mixing tee was increased from 6.0 gpm to 7.2 gpm. The change inratio of the hot water stream to the cold water stream served toincrease the temperature of the combined stream from 75° C. in Example42 to 80° C. in Example 44. Cut bicomponent fiber was added continuouslyto the cold slurry tank at about 320 grams/min. amounting to aconcentration of 4.0 weight % cut bicomponent fibers in the cold,bicomponent fiber slurry stream. After combining, the concentration ofthe cut bicomponent fibers in the combined stream exiting the mixing teeamounted to 0.90 weight %.

Compared to the microfibers of Examples 42 and 43, the microfibers ofExample 44 filtered better due to a higher degree of entanglement duringflow at higher temperature through the 1½″ pipe in Example 44 comparedto Examples 42 and 43. Microscopic examination of the microfibers ofExample 44 found them to consist of fine fibrils with a nominal 3 microndiameter corresponding to the starting diameter of the island domains inthe islands in the sea cut bicomponent fibers.

Microfibers of Example 44 were re-dispersed into water at high dilutionsand converted into sheet samples in the manner described in Example 42.The characteristics of the microfibers of Example 44 were noted to bequalitatively equivalent to the characteristics of the microfibers ofExample 42 opened at a lower temperature in the same plug flow openingprocess.

Example 45

The process of Example 44 was repeated where the length of the 1½″ plugflow pipe section used to contact the cut bicomponent fiber in hot waterwas increased to 110 feet. The effective residence time of the combinedbicomponent fiber slurry at 80° C. was doubled to about 90 seconds inthe process of Example 45. Filtration of the microfibers was veryefficient and similar to the behavior noted in Example 44. Microscopicexamination of the microfibers of Example 45 determined that themicrofibers were essentially fully open and comprised of individual finefibrils having nominal 3 micron diameter. High dilution forming tests ofthe product of Example 45 in the same manner as Example 44 did notidentify any characteristic differences in behaviors.

In Example 45, increasing the residence time in the plug flow pipesection of the apparatus used in Examples 42-45 did not demonstrate anysignificant improvements relative to the lower residence time used inExamples 42-44. In these examples, the 45 seconds residence time wassufficient to remove the sulfopolyester sea polymer to a sufficientdegree to cause opening of the cut bicomponent fibers because of thehigh temperatures used during the opening processes of Examples 42-44.In the event that a process advantage would be realized in running theopening process at the lowest possible temperature required toeffectively remove the water dispersible sulfopolyester polymer from thecut bicomponent fiber, the use of longer plug flow contact times aspracticed in Example 45 can provide a larger advantage than noted inthese Examples.

That which is claimed is:
 1. A process for producing a microfiberproduct stream, said process comprising: (A) contacting cutmulticomponent fibers having a length of less than 25 millimeters with atreated aqueous stream in a fiber slurry zone to produce a cutmulticomponent fiber slurry; wherein said cut multicomponent fiberscomprise at least one water dispersible sulfopolyester and at least onewater non-dispersible synthetic polymer immiscible with said waterdispersible sulfopolyester; and wherein said treated aqueous stream isat a temperature of 40° C. or less; (B) contacting said cutmulticomponent fiber slurry with a heated aqueous stream in a mix zoneto produce a heated multicomponent fiber slurry; (C) routing said heatedmulticomponent fiber slurry to a fiber opening zone with sufficientmixing to remove a portion of said water dispersible sulfopolyester toproduce an opened microfiber slurry with a temperature in the range ofabout of about 55° C. to about 100° C.; wherein the weight % of solidsin said opened microfiber slurry ranges from 0.1 weight % to about 20weight %; wherein said water non-dispersible polymer microfiber has aminimum transverse dimension of less than 10 microns; wherein said fiberopening zone comprises a pipe reactor; (D) routing said openedmicrofiber slurry to a primary solid liquid separation zone to producesaid microfiber product stream and a first mother liquor stream; whereinsaid first mother liquor stream comprises water and said waterdispersible sulfopolyester; and E) routing at least a portion of saidfirst mother liquor stream to a second solid liquid separation zone toproduce a secondary wet cake stream and a second mother liquor stream;wherein said second mother liquor stream comprises water and waterdispersible sulfopolyester; and wherein said secondary wet cake streamcomprises microfiber.
 2. A process according to claim 1 wherein said cutmulticomponent fibers have a length of less than 5 mm.
 3. A processaccording to claim 1 wherein said heated aqueous stream comprises atreated aqueous stream produced by routing an untreated aqueous streamto an aqueous treatment zone; wherein said treated aqueous streamcontains less than 50 ppm of divalent and multivalent cations; androuting said treated aqueous stream to a heat exchanger zone to producesaid heated aqueous stream.
 4. A process according to claim 1 whereinthe weight % of cut multicomponent fibers in said cut multicomponentfiber slurry in said fiber slurry zone ranges from about 35 weight % toabout 1 weight %.
 5. A process according to claim 1 wherein said fiberslurry zone further comprises at least one piece of equipment selectedfrom the group consisting of a hydro-pulper, a continuous stirred tankreactor, and an agitated batch tank.
 6. A process according to claim 1wherein said mix zone comprises at least one piece of equipment selectedfrom the group consisting of a continuous stirred tank reactor, anagitated batch tank, and a pipe.
 7. A process according to claim 1wherein said heated multicomponent fiber slurry in said mix zone hasabout 10 weight % to about 1 weight % cut multicomponent fibers.
 8. Aprocess according to claim 1 wherein the temperature of said openedmicrofiber slurry in said fiber opening zone ranges from about 55° C. toabout 100° C.
 9. A process according to claim 1 wherein said primarysolid liquid separation zone comprises at least one piece of equipmentselected from the group consisting of perforated basket centrifuges,continuous vacuum belt filters, batch vacuum nutschfilters, batchperforated settling tanks, twin wire dewatering devices, continuoushorizontal belt filters with a compressive zone, non vibrating inclinedscreen devices with wedge wire filter media, continuous vacuum drumfilters, and dewatering conveyor belts.
 10. A process according to claim1 wherein the weight % of solids in said microfiber product streamranges from about 10 weight % to about 65 weight %.
 11. A processaccording to claim 1 further comprising routing at least a portion ofsaid first mother liquor stream to: a) said fiber slurry zone; b) saidmix zone; c) said fiber opening zone; d) a heat exchange zone to producesaid heated aqueous stream and routing at least a portion of said heatedaqueous stream to said fiber opening zone and/or said mix zone; and/ore) said primary solid liquid separation zone.
 12. A process according toclaim 1 further comprising routing at least a portion of said secondmother liquor stream to a primary concentration zone to produce aprimary polymer concentrate stream and a primary recovered water stream.13. A process according to claim 1 further comprising routing at least aportion of said second mother liquor stream to: a) said fiber slurryzone; b) said mix zone; c) said fiber opening zone; d) a heat exchangezone to produce said heated aqueous stream and routing at least aportion of said heated aqueous stream to said fiber opening zone and/orsaid mix zone; and/or e) said primary solid liquid separation zone as awash stream.
 14. A process according to claim 12 further comprisingpurging said first mother liquor stream, said second mother liquorstream, and/or said primary recovered water stream from the process forreuse or to a wastewater treatment system.
 15. A process according toclaim 12 further comprising routing said primary recovered water streamto: a) fiber slurry zone; b) said mix zone; c) said fiber opening zone;d) a heat exchange zone to produce said heated aqueous stream androuting at least a portion of said heated aqueous stream to said fiberopening zone and/or said mix zone; and/or e) said primary solid liquidseparation zone as a wash stream.
 16. A process according to claim 12further comprising routing at least a portion of said primary polymerconcentrate stream to a secondary concentration zone to produce a vaporstream and a melted polymer stream.